My WD seems to flood when it is being driven, otherwise it idles fine. I can drive it about 200 yards and then it floods out. I have to drain the carburetor before it will start again. it has an aftermarket carb kit installed.

It sounds like during the rebuild the float level some how was changed to a higher setting. There is a tab on the float that needs to be bent in order to change when the float valve actually closes. Seems your float valve adjustment is allowing the carb fuel level to be too high which will create the exact symptom that you described.
If the level is fine then there can be a small piece of debris in the float valve seat.
Also.. if the float itself has filled with fuel it can be too heavy to float and cause the float level position to remain low even when the carb is full not allowing the fuel supply to be shut off. If the new o-ring for the float valve was cut during installation it can also cause your current symptom.
At this point I just think that a float level adjustment is all that should be required.
with the float bowl screws loose the bowl should never overflow in a static condition. If it does the float level adjustment is off.

Thanks for using FixYa.

Kelly