Hi Larry -
I have what I would consider "minor interference" with a few spots on the tank. I solved this by putting a few strips of an adhesive backed neoprene material between the tank and the cover.
It's really there for my own mental happiness. I certainly didn't have to force either the tank or the cover into place.
I can't say that about every car.
The biggest interference problem I had was with my "outboarded alternator" for the bulkhead reduction kit. That required me to cut a section out of the SS panel on the passenger side.
Rocky