you should change the old sending unit at the same time as the fuel tank. i covered mine with undercoat. i dont know about others. i actually covered the top before i put it in, too. my car is not exactly stock.

i would be happy to see you and your bird anytime you want to come out. mine is not registered and i am currently sans-license, so i cant drive to see you i could help you do the tank if you want to bring it out.