Fuel tank screw hole repair

[Normagain]

So what do you think? Forget about that clown, say this guy has a tank in decent condition and the only issue is an over size tapped mounting screw on the tank. He has to drill out one hole in the sending unit slightly. If he has a cleaned surface, proper screws and a NEW rubber gasket, will not the rubber gasket do its job still in a non pressurized system?