how to stop gas pump handle nozzle from spilling gas

I'm going to buy a later model short 2" filler neck for another application with the flapper valve. Cut the valve out of the neck on either side of it. Cut my Valiant filler neck and weld the flapper door in. I may also up size the original vent line on the filler neck, too. We'll see. That way, there won't be any openings around the flapper door for gas to still get around and slop all over the car.