No telling if it's authentic. Maybe a west coast knock off or update? Could have roots down in the continent, too.
Those panamera races caught the eye of the P execs and lead to the "panamera" custom model. I read about all that but don't exactly recall where or most details. Most likely it was in the PAC magazine, Cormorant, as a series, and I just threw out the last of my issues - yesterday - no doubt when you need something. It could be in another book or two I bought about the custom shop they used in Detroit. I've got too many things going right now, to do research for others.
Best to go to PAC and see if you can dig up some info under "panamera".

P racing history is small/handfull compared to other brands but has some limited period sport in most venues. P at that time was in difficulty/throws of demise and not supporting any racing teams/efforts. The L-heads suffered from the lack of HP to wt. That's another reason there's not many "speed" parts for them. cf, the ford flattie.

ps: I searched the Cretins racing and that's MC club, so who knows whats going on? Maybe our West Coast Rep, HH may have insight?

Pretty common. They make "universal" wells for replacement but they don't exactly fit the Ps. They take some massaging. It's a standard 15" bias tire well on the right side.
Maybe some posts on this, if you search.
They had a drain hole and apparently that caused them to get debris inside and clog up and rot out. I planned to change spare position in my project. Low hanging they could get dinged too.

How big is and how was the opening cut? Or was it rotted up top as well and just covered up?
That well's a separate insert piece and should be cut out a certain way/detached by the pinch/spot welds to allow replacement. Reweld and seam seal. If it's been butchered, may have to replace the trunk pan, and those are re-popped but not of exact configuration nor fit. I bought one and was dissatisfied. I would make one, if you're able.

Probably the best thing instead of a picture without perspective, is to get the/a dwg/dimensions. I have all that from before, I'll have to hunt for it, but I'm in the midst of changing computers and having issues. May have to exchange the new one I bought, so could be out of action for a week or more..

PAC was members only in a few places when I was a member years back, so nothing new, except maybe expanded territory? Declining membership may be forcing some cuts, etc. It wasn't the $ so much as the lack of need/interest for me. I get 2 much info every day, why should I have to clean out someone else's barn?

We seem to have an aversion to "free" in the digital age. Don't give Big Kev any ideas! ha, HA, HAAAA.
Microsoft is trying to claim that 'any' content developed on 'their' software and stored on the cloud is "theirs' to use under the "license". We have laws and copyrights in this country. Google recently got fined billions for clandestine use of users content so maybe someone will sue the billions off Microsoft next. We might get a few pennies after the Lawyers take the dollars. So much for the claims of safety and security with the cloud. It's always been a "don't go there zone" for me. I could smell it coming.
The AI push is fueling this, since it needs "big data" to be effective. And guess who has that, all the MAANG* companies pushing AI.

* - updated for Meta.

https://web.archive.org/web/20110813131600/http://avantisource.com/manual814.html

Not sure what year this was. Wasn't noted.
That was a dash pod mounted gauge, not stand alone/add on and I think Avanti were all 12 VDC by then. '40s is 6 VDC.
You really don't need positive pressure unless it's a boost gauge for super or turbo charging or downshifting to slow. To each his own. Gets no "points" from me. Wish U luck in your search for such a gauge. It can be done, maybe just not like you desire nor at your price point. My opinion.

Evidence the radiator support was cut and welded back most likely(common) for an engine pull. re:Weld was not finished.
Maybe that has something to do with the "gap" your showing concern for?

Other than originality, I doubt that ~1" space has much affect on cooling, so must be something else going on here. Are the lower/other pans installed? Is the correct fan blade on? Maybe an issue with the radiator. I had no issue with mine idling in the drive for extended periods, ie, no flow from the grille.
The pan on my 2365 did not go over the rad support either, so suspect that's the norm, flow direction, not complate sealing.
Any of the other P parts places may provide. I'd have to research all the various part #'s to see if there's a valid cooling difference.

Check and see if there's a part number stamped on your current part and run that down against what you're after.

I don't use nor recommend a vacuum gauge inside (nor prone to leak mechanical oil pressure.) I keep a 1" plumbed up in the engine compartment for carbed/vacuum actuated vehicles. Only need for troubleshooting/tuning - won't tell you much while driving, you'll most likely just get confused. They're inexpensive, < $25, oil filled, and only require a vacuum tee and a few inches of tubing, zip tie. I think you be happier with that approach, if you're flexible.
It's a 'figment' of the past thinking. Lots oof old myths have been dispelled in he automotive realm. That's why they no longer use it as an engine monitor.
My usual preventative maintenance schedule is replace all vacuum tubing every 5 years, like most rubber parts; belts, hoses.

If you want gauge to go inside you either have to drill a larger hole/grommet to feed the vacuum tube inside or install a transducer and run wiring. Response time will go down with a long tubing and more places for vacuum leaks. Response time is why they got away from pneumatic instruments in favor of electronic except for some special needs. You'll need a bezel for mounting or a gauge hole cutter. All that will raise the price to several hundreds which cost seems to be an issue.
Stewart Warner would be the period gauge du jour, they make a 2 5/8 dial series(auto) but the light is 12 vdc,(not req'd to work) since 6VDC was passe late '50s. So you'd have some "engineering" to do to make it 6V. The transducer is 12 V too. You can get a 6 to 12 convertor/more wiring. Lots of moving parts for something not adding value, but to each his own.

FYI: over on the left, there's a '48 fact book, that lists the 356 compression as 7:1.

You might contact Stromberg, they're still kicking, and may have a solution of something current that might work. ie, My standard Stromberg parts comment.

Might be one of those things were you're better off with the manual choke and why it was changed back in the day/if it didn't come that way... Is there a service bulletin out there? Manual chokes were quite the easy/best method back in the day. I used to have to go out under the hood in the cold and jam a screwdriver down the plate when the spring stayed shut due to inclement weather conditions. I would've liked a manual. Infinitely adjustible, where these mechanicals are "iffy".

I went through this on a choke 'modifier'. I got all the parts all the way from New Zealand, and it was "original" but wasn't worth the powder to blew it up. One of those "advancements" that was quickly ushered off the world stage. I went with an electric for next to nothing in cost. One of those be careful what you ask for things.

I bought a Chinese repop from Kanter back and wheel cylinders when I was resurrecting the '49. It fit and functioned OK, the lid gasket was not of the right material and seeped fluid. I just cleaned up the logo Wagner rubbers and put on the chinese cylinders - no markings.
I was going to resleeve, but it would've been a time issue, badly eaten so may have not been a good core anyway.
Usually, these repro parts are made by one source and shopped around by various vendors, so caveat emptor on prices.

I usually don't "endorse" product or services. I'm OK relating my experiences.
I'm a bit late looking back at posts.

I had some "pot metal" and steel trim parts to do that I exchanged/replaced with some used I acquired, while I'm working on my other car.
My usual source quit doing pot metal and trim, only does bumpers now. So that's one place, if you need bumpers done. His "competition" quoted me 56 weeks, ie; over a year to get them done. I've never used these guys, but talked to them at the Auto Fair.
I contacted the people I used before, Advanced Plating" and they were about half the wait. www.advancedplating.com
They were a bit high in price in my opinion, wouldn't budge off their estimate, but can do "show chrome" quality and specialty finsihes which is a bit more than my driver needs and they already had my parts, and it costs about $75+ to ship one way which I had to pay if they replated anyway. If I didn't already know their work, I'd not pursued. They did all the Packard chrome quite a few years back and it's looking well in storage. I had them black chrome the divider on the windshield to make it less noticeable. They beat their 22 week estimate by a few weeks, not as much as I first thought.
First, I'd search around the "bays" and such for used or rechromed parts, they might be cheaper than getting yours replated now. Eg:The purchased pot metal set was just under the cost to replate about a wash - no wait. I bought a set of 1" wide spears for around $300 that were perfect. They charged me $741 to do one now. But it's flawless and better than anything that came from the factory. So show chrome is not restoration in my opinion. Another show chrome place advertised on TV, I dealt with was even higher than Advanced.