I am having the same problem with my stock carb that countryboy is/was having. I bought a carb rebuild kit and have adjusted the float and replaced the needle. (shindy carb kits are of terrible quality). It is still leaking. Carb was thoroughly cleaned and inspected. I even installed a hose and put it to my mouth, blowing air into the carb with the bowl off and would move the float manually up and down...it worked great. However, it still drips when gas is running through it.
Part of me wonders if the ethanol in the gas has done something to the carbs, but I don't know.
I thought in order to run a 38 a/s carb you had to remove the airbox or at least the lid....Is that not the case?