Yes sir, that would do the trick. You could also crimp the port shut and weld or braze to seal if you're looking for a permanent modification. I would go with the fuel line, bolt, clamp route, being if you ever wanted to utilize that return port, it's still available.
As far as Tallhair's question, yes one factors of that return was reducing the chance for vapor lock. Now a days, it is a great idea to run a return line being a great majority of places have ethanol in the gas. Well, lets just call it as it is...corn alcohol. Anyways, our old engine designs and deadheading the fuel to the carb leads to vapor lock a lot easier with this funky veggie gas. Cycling that unused fuel back to the tank to cool down without a doubt will help with that sort of issue. As far as fuel tanks, no they're all not made equally. Typically you get what you pay for. The spectra tanks and fuel sending units Jeff sells at 521 Restoration are good. I've bought (2) of their sending units and both gave accurate fuel levels. My bird has a spectra tank as well. Great quality. The Vacuum nipple and clamp may work. I brought up the fuel hose because it's made/known to be fuel resistant and not degraded by fuel over time. I would check to see if that vacuum nipple's material is rated as fuel resistant.
Good luck fella's.
