I did exactly what you are thinking of doing on a Briggs 12-horse carb float. My float was 1/4 full of gas but no entry hole visable so I drilled a small hole in the top close to the pivot point and drained it good and then patched the hole with J.B.. So far it seems to have done the trick and stopped the engine from surging as it did with the float 1/4 full of gas.
P.S., The residue free cleaner that I always use instead of brake cleaner is el`cheapo Wal-Mart brand carb cleaner in the spray can.