Also...and I remember Jeff mentioning this to ME,when I was going through My 29's...the floats will sometimes come into contact with the carb body itself,causing the float to hang up.If I remember correctly,the remedy for this,is to gently bend the floats in the opposite direction of where they come closest to the inside of the floatbowl.I can't recall if there's much side-to-side play on the floats(riding on the pins),but I don't think there is.Have a look and make sure there's clearance on the floats.
And on the vent lines?...when I first got My carbs all cleaned out and floats set,I made the mistake of bridging the vent line from one set of carbs,across to the other set,creating a vent-lock,which resulted in fuel seaping out the air-side of the carbs(same as You desrcibe)...DO NOT DO THAT! LOL...run 2 seperate lines from the vent nipples,and route them so they hang over Your swingarm pivot somewhere.
I'm guessing that COULD be why You're getting fuel seeping out the airside of the carbs...hopefully,cause that's an easy fix.
Other than jetting,I haven't had ANY problems with the 29's since then.(still working on jetting,but I will get it)