The junkyard and tape measure method works. I bought my seats for my 1957 Task Force through eBay (they posted the measurements).
As long as the measurements are close most seats could probably be made to work. I needed bucket seats because of shifter clearance issues. I have a
three speed OD trans with floor shift. The seats I bought were from a 2001 Audio. I just made an intermediate submount and it worked fine.
Also, I was able to keep the electric control for seat positioning (didn't need the seat warmers). Since the seats were "leather," I was able to
dye them a more appropriate color. It was confusing for me at first also, but it is one of those things, that once you commit you can make it work.
I do sometimes get comments of "Not period correct." But none of those people were in the garage when I had to figure this out and configure
the install.
don