The carb parts need to be stripped absolutely bare.........then lightly sand blast, clean off thoroughly then mask off very carefully.........paint in dull eurothane silver in 2 pac........Look at paints that Aeromodellers use, this must resist methanol fuels, castor oil and so on. The original carbs almost always drip fuel unless you keep the bike dead upright like on a Dave Hills stand......I prefer a good side stand like off a Kawasaki, and fitted dozens of them to bikes now..........The paint will eventually lift at the points where fuel leaks from, mostly the bleed hole at the base of the main carb body........You can use dull or matt clear as well over the base paint and this seals the paint.........It is a tricky job that takes a bit of care to get right.........Modern fuels attack paints no matter what they are.