A couple of years ago, I went up north to have a look at a "Slightly Modified" FC (thats what the ad said).
Cruddy car it turned out, but the amazing fuel filler left me speechless, especially when the fella tried to tell me it was legal.
He had cut it off 3 inches from the base & had taken great pains to fit a Brand new cap off an AEROSOL CAN!!!!!
But he warned me, "It HAS to be a tight fit!!"
Weird!
But if you are looking for a better solution, ACE has the right idea. The 1957 Chevs had their filler behind a section in the tail light housing. Looks cool.
4hammers