Bigfoot 60 4-stroke non EFI - fuel in oil

[Prospector]

Engine is a 2001 Merc Bigfoot 60 HP 4-stroke non EFI (1F60452YD). I drained lube oil and got 4 qts - 3 qts oil and 1 qt gasoline in solution. I verified by OHM testing that there are no problem with thermostat, temp. sensor or enricher. I am changing t'stat and temp. sensor anyway. I opened fuel pump and diaphragms seem OK but I will also change the inboard diaphragm with the plunger. Engine ran fine all last season but started to run rough just as I was putting it up for winter. Engine is stored vertical. Would a bad float in one of the carburetors cause this much fuel to suddenly get into lube oil in a short amount of time? Is there something else I am overlooking?

Thanks

[boats.net]

Carbs is the most likely cause for flooding, if carbs are ok the run a compression test on engine.