If the water was in there long enough to grow "white fuzzies" on the aluminum inside the carb, then it is possible that the smaller passages in the fuel circuits are also blocked. Thin wire and careful inspection of every part of the carb that flows fuel, will help you determine the extent of the damage, and whether it is repairable. Otherwise, it sounds like a simple tuning or installation issue (gasket on wrong, bad vacuum caps, that kind of thing).