Small addition:

The National rules allow also use of a remote needle valve, other than what came on the plane or add one to an engine which did not come with one. Well, not any, you can't change the mixture in flight, but who would want to do that?

I have three (3) Thunder Tiger carburetors which have had the needle valve assembly break out of the carb body. Rather than buy new carb body with the same weakness, I JB Weld a piece of the 1/8th in. aluminum tube, which came with the tanks, into the broken hole/socket and use an OS remote mount and needle assembly. Works fine.

Ken Erickson