Make sure you pay attention to the well plugs on the bottom of the bowl. Old well plug gasket material is still stuck on these; either clean/inspect and make sure you use a kit with the replacement gasket, or remove the soft plugs, drill, tap and plug the bottom of the wells to prevent gas leaking back out out of the carb into the engine. To me, that's always been the worst design feature of the Quadrajets - otherwise, they are great carbs, easy to work on and last forever.
Just my opinion -
Anyway to fix the well plugs without drilling or removing the carb and rebuilding it?