I think your plan will work fine. Need to get the correct sending unit for the car with return nipple. Agree the gauge will likely be a bit funky with the re-pop sender.

You probably already know this, but leaks at the sender are often caused by thinner material in the re-pop lock ring and gasket. There is just not enough clamp. Cleaning up an old lock ring if you have one would help. I don't know the source for a thicker gasket... maybe you will get some suggestions or try a couple sources. You can stack 2 thin ones to get it to seal if all else fails.