Usually, when you change a part and use several different brands and get the same failure, something else is wrong. Could be wiring, generator, or gauge, etc..
My friend went through 6 alternators on his truck and I asked him why the service guys hadn't caught on to look for something else. I'd been collecting scalps after 2!
Make sure you read the procedure and properly polarize.

Can't necessarily apply other manufacturers techniques to Packard, like auction speak, "number's matching". eg; It' pretty clear my Cad engine and VIN numbers are the same in the year it was made, and I could get a copy of the build record easily. Not available here.
If there's no documentation with the vehicle about the only thing is check the castings for dates that are appropriate for the model year. The location of the stamped engine numbers changed if I recall correctly, so another "tell", ie, in the right spot.
I think Neal's book(s) has a listing of engine numbers and/or body numbers by year, but my copy's for 22/23 series, but going from memory that's not fresh. I know I researched mine and concluded without provenance it was unmolested based on mileage and condition, etc.
PAC roster keeper may give a better answer, but I doubt it.
I don't know anyone tabulated what records remain as the remaining files are split between PAC and Studebaker museum. There's several "Packard" museums too. Bodies mostly are second party after '40s and Brigg's was bought out in 50s. So the trail is brushed and grown over.

Not buying the kool aid here.

https://en.wikipedia.org/wiki/American_Motors_Corporation

Brake manufacturers made the masters not car companies. AMC did no direct parts manufacturing, they sourced all their items. They bought from different places in different years. So did Packard to some extent, like the bodies. If you ever owned a Jeep, you might have a Ford engine, GM trans, Essex wiring, Dana axles, Spicer gears, and lights from Grote, or someone else.
Wagner, Bendix, etc created the brake parts, owned the patents, and sold them to the car companies. Packard (post war) used Wagner as some of the others where owned or controlled by the big three.
This is not a task for someone that doesn't know brake systems. It's a safety system, so needs the right engineering. Volume and pressure must match the wheel cylinders. DOT controls part of the system, sets standards usually off SAE or other recommendations. Not saying it's not commonly done, but can lead to accidents if not done right. Get in touch with a certified mechanic.
If you look at the single castings, there's usually a second port cast but not drilled and tapped. The piston assembly has to change to operate two ports.

They're just an aggregator site of all the online sales ads. I use them a lot to look for cars, but you still have to deal with the person selling the vehicle.
There should be a contact on the ad for the seller. Email doesn't seem to be too effective, so phone call is still best.

Story isn't straight. First no keys, then ign key is thin and bends?

You can get a "universal" ignition switch that comes with keys, if you just want to fire it up or check things out, temporarily. I recall the P ignition switches were a bit hard to come by. But the lock set is common. Mine was missing completely, but I had keys?
I suspect with the virus, etc. locksmiths aren't as happy to come to you as in the past, so you may have to take the parts out and take to them or send out. If you don't find anyone locally,
www.jessers.com can make keys, rekey, or repair the ignition cylinder or door lock cylinders. He's done work for me. He's located in Akron OH.

And if you had one, it was only a "partial" filter. A side stream of the oil was sent to the filter, not all of it. Pretty common back then. My decade later '58 Cad is similarly equipped(partial filter). Full filtration didn't come til '61 model.
Oil was fairly inexpensive, ~20 cents/qt post war and was cheaper to just change it frequently than invest in filtration.
Many people just topped it off at the pump and never bothered with changing.
I believe the shop manual calls for periodic scraping out the oil pan. Sump was pretty much a place to settle out the solids from combustion. They used to sell remote oil plugs, so you could warm up the motor and pull the "plug" and drain it while it was hot, often in some inconspicuous location, so you didn't have to dispose of the old oil.
Don't know how many of these leaked or were accidently bumped open during driving...

I think they're 5x5 pattern. There's a way to measure for the right bolt pattern, so search it on the internet. Tire places have it. The only other thing was the spring clips, with or with out, depended on year/model.

Another site confirms as of last week that "Then and Now" weymouth MA is still in business.

They have a facebook page, but the last post was mid 2020. I don't do facebook. No mention of status but contact links were nonfunctional. There's a phone number on there. The "new" URL; then-now.com is also non-claimed.
Not my day to keep track of all the small businesses that may or may not survived the epidemic.
They were a good source for me.

I'm pretty sure I found my dampener at "Then and Now" automotive parts. It's been a while so not sure if they still have inventory.
www.then-now-auto.com