I found EUBMW (www.eubmw.com) has good prices for 32mm Bing rebuild kits. The float plate pin is driven out on the side w/out the knurling. The knurling keeps the pin in the body.
Generally, I found tapping the pin using a plastic screwdriver handle is enough - where the screwdriver is used like a punch while holding the carburetor body in your hand. Another option is to use some channel lock pliers opened wide to squeeze the pin out of the body. The pin is brass and the carb body aluminum, so minimum force is needed.
I had an occasional carburetor flooding problem with a Bing alcohol proof float kit installed. The problem was varnish from sitting 16 years caused the floats to stick when the float bowl was low on gas. The varnish still remained even after soaking in carb cleaner. Polishing using Brasso and pipe cleaners solved the problem.
Fuel bowl overflowing suddenly occurring is caused by: the float sticking or sinking (i.e. bad or sticky floats), the needle valve damaged or deteriorated, or debris at the seat preventing sealing. The easiest to check is debris at the seat which often leaves residue at the bottom of the float bowl, next is removing the needle valve and inspecting the needle valve and carb body seat, finally the floats can be checked for their buoyancy in gasoline (which is messy and unpleasant). I think most people just replace the floats rather than test them if they are the most likely problem. Good Luck!