If the carb is flooding, the gas is going to leak out the lowest point it can. I would expect it to leak out between the carb body and the flame arrestor, but if that has a good seal, then the choke shaft is next up.
Sounds like the float is no longer shutting off the float valve, and the bowl is overflowing. I would remove the carb (catching the gas) and rebuild it, including a new float valve. If you don't have a fuel filter inline, this would be a good time to add one.
Don't blow up your boat - be careful.
Al
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