67 FB Fuel Tank

Nope, your floor is bent, it's supposed to be flat, with just a little strip-caulk to seal.

you should be able to bend that panel easily, as it's spot welded to the panels around it, but still semi-flexible. If you cant move it you might consider making a filler panel out of 20 gauge sheet metal and just riveting it into place if you don't have a welder. If you're not painted yet, this should be a simple fix, if you're in paint and already detailed then you have to get creative. This is why it's so important to mock up before paint and detail; you can find things like this out before you've spent money on cosmetics. The worst case scenario that I can imagine here is that somebody has replaced trunk floor panels without test fitting the fuel tank.... in which case you'll have to either reinstall the front axel arch panel (inexpensive and available from many different vedors) or make a filler to compensate for somebody's mistake.

Good luck!

I suspect he'll be OK, even if it's not welded together properly, a little extra strip caulk at the corners should take care of irregularities eve if it's already painted.