low power when hot?
fuel filter is vertical between the fan and the manifold where the hardline comes up towards the carb
It's not just whether the fuel filter is vertical or not. It's the routing of the fuel line in the stock location absorbing heat as it hugs the block.
What you want to do is remove the existing hard line. Then make a new one using new rubber hose rated for fuel use. Today's gas tends to "boil" at a lower temp than the stuff that was available when these cars were new. The recommended fix per SlantSixDan is referenced multiple times in this section. (easy to search) I did this using a couple Holley 90 degree tubes purchased from Summit. Basically, one 90 degree fitting is screwed directly into the fuel pump outlet so it points straight up toward the valve cover. The other is screwed into the carb inlet and points directly toward the valve cover. Then new 5/16" fuel hose connects them with the fuel filter now located on the side of the engine kinda behind the alternator. This should solve or prevent any fuel perforation issues.
As already mentioned, verify the heat riser operation.
Also you might try swapping another coil. Sometimes they go bad when hot.
Get a timing light or rent one for free from a large auto parts chain. Do not set to factory spec but set it between 5 and 10 degrees BTDC (Advanced) with the vacuum advance hose disconnected and plugged. (Golf tee)
From what I gather, it is hard to find a good 1920. I'd be inclined to rebuild your original. Check with Daytona Carb to get a good kit AND a new float or even a good used one. I bought a new float for my Carter from them.
Exactly what happens when you try to drive up your hill when hot? Have you tried putting the trans in low and crawling up the hill at 5-10 MPH just to get it home?
There is no reason your car cannot run like it did in 1972, or better, assuming the guy who rebuilt the engine knew what he was doing. Unless you have paperwork showing the work done, you won't know if it is .030 over or not unless you pull the head. The bore diameter can be measured but oversized pistons should be stamped .030, .040 etc. on the top.
