Carburetor floods with fuel and overflows until it leaks out

Hello,

A carburetor can only flood if the float is sticking/misadjusted, needle and seat is not sealing or if the supply pressure from the fuel pump is too high.
Have you checked if your fuel return line is not blocked?

You did not mention if the fuel pump is a mechanical or electric unit.
Using a fuel pressure gauge check the fuel pressure at the inlet side of the carburetor.
It should not be higher than 0.5 bar, 6-8 PSI.
See image below for fuel pressure gauge example.

Please let us know how you get along.

Cheers, Boris