I have a Snapper with a 5hp B&S Quantum I bought new back in 1999. I thought the tank had started leaking fuel but after removing the air filter to get to the grass catcher duct nuts to remove the tank, I can see that the fuel is actually dripping from a small port on the carb in the bottom of the air horn opening. If this was my car, I'd be thinking stuck float with fuel leaking out of a vent? Does this sound close? Are these carbs rebuildable?
Here's a generic photo I got online. The drip is coming form the small port right in front of the butterfly. I think the right one.
You have the correct assumption. Float valve leaking allowing the carb to overflow. There are about 3 different carb kits used on that style of carb, so be sure to get the model number info from the engine to make sure you get the correct kit.