My shop manual, '49, has a specific section on the convs. Would help to seek a copy out for your year. I think they're on here over in the archive?
Quick peek at the electrical diagram wouldn't hurt either. Clicking usually is a relay issue, but pure guess from here. I'd disconnect and jumper out the pump and see if it turns/works. One pole up, one down, is typical. Then work up stream.
There's only a few other conv top places, easy search. I doubt you'll find a P pump or parts without knowing who made it/model number. Not easy in P speak parts lists. Most likely best to just replace with something new and equal, if toast.

Haven't bought any crates in a long time, usually fairly costly, if custom size and strong enough to stack many high. I had a '50s fender shipped recently and the guy made one and upped the shipping cost quite a bit.
One option also, not cheap,~$200 ea, are transmission storage cases. Made out of plastic, leak proof, specifically for transmission storage. Will last longer than a crate. Easy search.
Most trans shops, just use a rack. Heavy self assemble storage shelves are fairly inexpensive at the Chinese takeouts. What I use for misc parts. Doesn't pay to skimp here. Another cheap way is industrial shelving is frequently found at auction. Industrial grade for pennies/dollars.

Just search CA auto swop meets and U'l get many listings.
I'm on the "bad" coast so don't follow, per se, but have knowledge over the years. Hemmings and other pubs for leads, but not like it was, page shrinkage galore. There's a rod section in Hemmings.
Duly noted, "waiting 30 years" for one, makes them nearly unobtainium. But they come up, need to cast a wide net. Now I wish I would've bid... Even if you find, owner may not want to part with. Seems like stuff I save no one wants or prospective buyers are cheapo.
Another thought: The Frod V8 flatties have more HR following/numbers, so some of those guys may have leads for straighties. P world/survival is comparatively small. There's commercial flattie rebuilders, hot rodders, etc.

Couple simple checks;
Fuel pressure - should be below 6 psi.
If fuel rich suspect, tail pipe will get coated in black soot.
Bogging down is usually a lack of fuel. When the throttle opens or the accelerator pump actuates, insufficient fuel flow for the air intake - becomes not flammable and dies. Check the fuel/fuel tank & line, it's been sitting 5 years and may need cleaned/dried out and fresh gas. The old accelerator pumps had leather cup seals and can dry and harden, same with paper gaskets that been soaked in gas/ethanol, so may need a partial carb refurb.
Put a timing light on it, if mark's not moving on accel then the timing advance is not.
The other is a bad vacuum leak, but they usually indicate with a rough idle. "Vacuum idlers" are affected.
Weak spark but less likely. More fuel needs strong spark to ignite.
Obstructions. Sitting and subject to all sorts of things happening. Check air cleaner, intake/exhaust, etc. Mice will nest in eh damnedest places. Once my motor home wouldn't start after winter storage. I was traveling so had it towed to mechanic because I had a trip planned for weekend. I'd had fuel tank issues, so that was suspect. Air cleaner was full of mice nest.

Those must be "new" as they weren't out there a few years ago. Even the AL customs where flat tops.
Some ugly welding? Not machine made.

If cooling becomes an issue, add a fan shroud and make sure all the front sheet metal is back on to direct the flow.
Usually, one needs extra additive with mixed metal systems, but frequent coolant change with good grade today works.

Shouldn't be too big a deal to recore an original. Fair quantity out there. I had mine done. Cost maybe same with fabrication.
There's the universal "wrinkle" hoses that take the bends better if fitment is poor. I took one over the bow by the purists when I posted mine.

switches are more rated on amperage than voltage. However, lots of junk coming from offshore, caveat emptor. Much like wire size, there has to sufficient contact area for current to pass without heating. It not just at shutoff, but how it works when turned on. Voltage only affects the insulation, per se. Compare to hydraulic flow. Current is the volume(area dependent), Voltage is the pressure(containment dependent).
It's typical in 12VDC- to put the switch on the neg as it prevents sparking when reconnected. I'm not sure either is appropriate for + ground. I haven't studied that one. Make sure the instructions specify and not just the same as 12. Could be shocking experience.
I tend to use AMG so they aren't as predisposed to drain cycling failure. I can forget to disconnect the switch, too. Charge it before I use.
Positive grounds will leak off continually as it also plays an anodic protection role, preventing corrosion. Negative ground only passes through the body when flow required. It's one of the inherent issues with 6VDC +, the other is it requires twice the amperage/larger wires/contactors which drains wet cells faster. The old generators/VRs were only 30-35A rated, so if you didn't run it long enough, the battery never gets fully charged. Typical 12s today are 45-60A or more.
Those charge/discharge wheatstone bridge ammeters don't tell you much about battery condition. Just the difference in technical understanding of the times.
If you want original you have to put up with original.

I saw some come to auction this summer, some large parts collection. I almost bid myself, but got enough clutter, lack of motivation, and pickup was too far. One of those I shoulda bought all the lots, but it was already in multiple storage units, so even the owner didn't have enough space and monthly fees accumulate faster than value. Once it's gone...
Ebay is a bit chaotic/hit and miss. You should plug into the auction network(s). I use proxy-bid.
Since aluminum, also have to check it thoroughly that it's still good. Won't see on a internet photo. Can repair cast aluminum if not too badly corroded. Never seen any numbers made, but doubt there were that many ever made, especially 4 P which was low production/not hotrod favorable.
The attrition rate may also be high. Period hot rod parts is a narrow niche, hoarded by period old timers. CA would be the place to search. Hot rod culture was hot and home there in the day. They have large parts swop meets regularly at some venues. East coast, Hershey / Carlisle twice a year but AACA mostly. There's a guy on here that hawks parts, ask him to be on look out.
It's even happening to modern vehicles. My friend needs a trim part for his foreign car that's obsolete. It's even harder to track those import parts. Internet has no update. Searching past posts often vapor.

I checked, one can also get these/others from the Nat Pack Museum store website, but my sister got me these somewhere around Akron.
Nice light weight material for southern living.
Nostalgia: It's within my origin's turf, appropriate as well. Rt 422 was "thee" place where all the restaurants were and closer to the Grandparent's farm, along the way so to speak. Ate plenty of Mr. R's pizza and other restaurant food from Warren in my youth. First Micky D's and Arby's in the area, too. Not like now, every other corner gas station has something drive up. We had enough gas stations and were branded but local/independents owners mostly. Including ours - rented out. People ran out of gas, but I think it was more from cheap auto fuel gauges and being poor. Gas was not as dear but people still drove to save a pennie or two. Who'd a thought it go from 29 cents back in the day to >$4 off and on now. I think when they opened our station in 1920, it was ten cents/gal. I'll have to looked at the picture. A motor head's dream to work them/hang out. I worked in Warren at a gas station, my deceased cousin ran, during college and got unsuccessfully "robbed". But did take a stitches needed hit to the head, little didn't they know it was hardest up there on me. Robber used the wrong end of that gun or I'd not be here.
It's not like that now, my head or Warren. Kinda like Packards, never be the same.

Usually pretty easy to identify SS vs chrome trim. There's a noticeable difference in luster. SS will rust stain but usually won't pit.(saltwater excluded) Pitting is common in white metal chromed trim. The white metal goes bad over time too even if the "chrome" is good.
Just because the chrome is off/thin, doesn't mean much as it's easy to over clean chrome and wear off the chrome layer with the polish compounds. It's only on there at a small amount. Copper and nickel do the heavy plating. If it's dull then likely the chrome is gone - nickel showing, if the copper is showing the nickel is gone too.
SS can be heavily buffed/polished as it's the same metal all the way through. It's just thin metal to start with.

These reservoir types need the reservoir drained and cleaned out after taking out the filter element or you're just reintroducing contaminates.
It's one of those it depends questions. If it's stored in a dry place and not driven much then rusting is not that much of an issue. There's always one or more valves in the open positions so it'll breathe a bit. Water is part of combustion so have to warm it up to get the water out the exhaust system.
If it's never been rebuilt and has sludge in it, then that's another case to watch and more frequent doesn't hurt with modern oils, since more detergents. They didn't even put detergents in the early motor oils, aka "ND" or straight weight.
If you're regularly driving and moderate speeds, 3-4000 is probably good. A "partial flow" filter isn't going to see the same amount of flow as a "full flow" filter so the element won't catch as much per mile. What I do when I get a new vehicle is check the oil every 1K for color and lubricity until it needs changed then round down and use that interval. It'll tell you if it's getting used up, dark and gritty.
But today you get free oil changes, synthetic oil, and some have a oil checker/monitor tied to the computer so only works on the older cars/diesels.
Depends how long you want motor to last too. At 3000 or less interval you're probably at max life because they oil isn't close to used up when changed.