Your carb might drip because the float valve is leaking or because the float level is incorrect. It sounds like you are chasing those two down.
A carb can also leak (drip) because the main jets inside the venturi are not sealing properly, so the fuel leaks out and drips out the inlet of the carb. Make sure the seats are clean, the jets are snug, possible put a light coat of sealant on them.
Or the main jet has been installed with 2 little gaskets on it and in the hole. This lowers the tip of the jet and, even with the float level correct, gets the gas liquid level too far up the jet. So check where the main jet is screwed in and confirm you don't have the old remains of a gasket down in the hole.
Hope this helps you clear it up.
Is your new float valve a solid metal needle or viton tip?
