Before you open up that wallet, try renovating the float valves. Check the overflow tubes too, they are worth a look anyway.
The float level has to be set to spec or the carbs will never work properly, you can't fix a dripping/gushing overflow by diddling with the float level anyway (as you found out). Do one at a time so as not to mix up the parts.
Take the valve seat out. If the needle part is attached to the float take it off the wire clip. Clean the parts with solvent and a Q-tip. If your needle has a rubber tip.... well then open up the wallet I guess as these are not repairable.
Metal needle tip: Inspect the tip area, using a magnifier if you have one (pretty useful). Look for a groove ringing the needle a little ways from the point. If you see that, the needle is probably done but if there's just a slight blemish ring or a line then it should be usable. Hopefully you have an electric hand drill, battery or plug-in. You want to chuck the needle gently in the drill. Wrapping a few turns of electric tape around the needle is good, it protects the needle and rounds off the 4 sided part to go in the 3 tooth chuck farly nicely. Have the actual point sticking out a ways. Get a soft cloth and some Brasso or Solvol Autosol and polish the needle tip as you spin it in the drill. Don't go mental - you want to smooth it off, not remove a lot of metal.
Brass needle seat: Inspect inside where the needle actually seats. You should see a shiny ring of brass where the needle rests, if there is a blemish, crack, hole, or any damage there you should replace the set. If it looks OK then get out those Q-tips. You'll see the cotton is wrapped clockwise on one end and counterclockwise on the other. Clip off the counterclockwise end of one with wire cutters, axe, machete... whatever you have. Chuck the cut end in your drill. Twist the cotton tip end with your fingers to make a bit of a point. Coat the cotton tip with solvol or brasso. Spin it up and press the valve body onto the cotton, polish for 10 seconds or so.
Last step is to put a bit of polish on the needle tip and insert it into the seat. It projects enough so you can just hold it by opposite "flats" beween your fingernails as you turn the seat a few times with gentle pressure applied. This hopefully matches the mating surfaces, you do not want to grind a groove in the needle so take it easy.
Clean the needle and seat thoroughly, make sure the spring pin is working freely. Replace and test. They are easy to test, get some aquarium air tube and slide the seat in one end. A bit of heat on the tube will allow it to expane and fit the seat diameter nicely. Insert the needle, immerse the valve in water, and blow in the tube. The valve should be bubble free with the needle just seating, pressing on the pin with your finger with less force than it takes to compress the spring. If it bubbles even with the pin pressed, buy a new valve set. Do not attempt to just replace the pin or seat, you need the set.
One last possibility: the seat has an O-ring. If this is damaged or missing or even just old and really hard, it can leak around it. I've seen drips from this, but I don't believe enough gas could get through the clearance between seat and carb body to have any flow of fuel leaking.
I recommend OEM KeiHin float valves from Honda. I've had bad ones from aftermarket kits. KeiHin used the same valve on many carbs, so as far as I know they are still available.
