I was thinking about doing the same but wasn't sure on how well the old tube and weld around it would drill. Any tips on the soldering? No issues with the sender connection overheating /melting?
I drilled the sender and used a threaded tube with a nut and gasket on each side for the return on a 3/8 pickup tube sender that didn't have a return provision.
Table lamp parts actually, and it's been that way for thousands of trouble free miles.