I had the same "pissin' overflow" problem. I read hundreds of archive forums (most with two bits from WG). I pulled the carbs and found a few things.
First problem was double gaskets on three of the carbs. Some gas was seeping from the bowl gasket on #2. See photos below. I thought this was just slack mechanics. You should be able to see the complete gasket on the Carb Body and the partial (old) gasket from previous cleaning still attached to the bowl. I'm assuming that at some point some pro was teaching some rookie shop hand how to clean carbs on the #1 (the clean one with only one gasket) then told the rookie to do the other three.
The #2, #3 and #4 carbs had something like caramelized napalm goo all over the float hendge, jet needle, and down into the jets. Those three carbs floats were frozen in place with the goo. The springiness on two of them freed up quickly enough. The 3rd one pushed in but didn't spring back. On that #3, it pushed in like a hydrolic arm and didn't spring back. So I believe that my overflow problem was caused by carmelized napalm goo mucking up the float action and probably sealing off the jets. Go figure.
One question, the brass barrel shaped "Throttle Valve" in the upper half.. all 4 were in various hights in the carb and varius freeplay in each. I didn't have time to break down everything and clean it today. I'm just curious what am suposed to expect once it was clean and back to perfect?
Tomtom