I'm working on my 47 Ford coupe and thinking about using a 60s Mustang gas tank and it's going to be a snug fit (cut the rotted floor and drop the tank in place.). I'm thinking to get it to fit I'll have to trim the flange on the tank in certain parts. My biggest concern is trimming the flange too close to the weld.
My thinking is to use the Mustang tank to double it as the trunk floor.