Knowing where your carb is leaking would be helpful in order to give you a reasonable answer.
Below is a couple of suggestions:
First check the float level before changing the float valve. Often times if the float level is too high the fuel will run over the top of the main and cap jet. The other possibility is a fuel leak at the base of the main or cap jet; this can be corrected by using some gas resistant sealant on the gaskets.
Regarding the float valve, I use the original type; purchase them from A&L Parts in Canton, CT.
Ron