Any ways to do this if I don't trust my welding enough for a fuel tank? Haha! This is a great idea and lets you use easily available and robust oem pumps.
I got a friend who welds to do it for me, if that helps.
We cut plates for the factory sending unit and fill hole so we could put some low pressure air in the tank and check for leaks and fix them. Probably worth sealing the tank with some of that liquid stuff, too.