Fuel tank straps, add felt or rubber?

For what it's worth, I put a new tank in my '71 Dart awhile back. I was in a hurry and just slapped it in with the sending unit that came with the tank. The sender is a piece if crap and I'll be digging it back out so make sure yours works properly before installing your tank. My car also had the wacky fuel filler tube with the '71 only gas cap so I used a later Scamp filler tube. The problem I'm having is a fuel leak at the rubber grommet. It appears the leak is due to the filler tube being inserted too far into the tank. I'm thinking the fuel tank is mounted too far to the drivers side. The filler neck also doesn't mount flush to the fender- sticking out about 1/8". The mounting holes in the quarter panel aren't clocked properly for flange on the filler tube either. Just a few observations that might help you get yours right the first time.