Its not the gas, because the pressure of the carbs
air horn against the main body does seal it with no wicking.
You also mentioned that it wicks after you turn the car off,
if it were the gas it would also wick while running. You say
it wicks from the edge, sounds like your gas is boiling on heat soak
& the level is rising to soak the gasket. It should not
leak gas Cliffs carbs dont wick gas and there the same type of carb,
so it must be fixable.