Fast and a fuel filler idea.

[Accelo]

A YouTube video. Guy has a Hellcat motor in his 68 C10.

https://www.youtube.com/watch?v=SDzpqSvqJz0

Chevy grill and GMC tail gate so he is not bias.
Nice truck with a fun video.
Check out the gas filler at 4 min into the video.
He has a removable floor section held in with magnets.
Kept the stock tank fill as a dummy.
One way to solve the "how do I get this round filler installed on a corrugated floor.

Some low $ stuff, but not the suspension, brakes and motor.

Cheers.