I too prefer the X rings (proper term is quad ring) I'd also suggest looking at the bottom side of the wells as a possible leakage point, remove the carb, lift it straight uo, don't tilt is si the fuel stays in the bowl... remove the screws & lift the body off the baseplate, if theres fuel in the base plate where the well extensions sit you've found your problem... Typically a good cleaning with a dremel & a coat of JB Weld will cure that issue... It may have been an old leak or when you rebuilt the carb the cleaner you used may have attacked the old sealer...

Edit, I see while I was on the phone MM covered the wells pretty well... Well Well