The choice of carburettor depends on aplication.
Idealy some one needs to go through a box of junk carbs from the pre emission days and identify something that is easily modified to fit toe GX head, has an adjustable idle and high speed screw and can be addpated to the clone governer link.
This will eliminate 70% of the troubles the first engine has and its something that has abit more pep too it thats OK too.
I am leaning towrads the Carter N used on old Onan, Wisconsin, Kohlers, Lauson and some Clintons at this point. But I am not the kind that sits on a lot of old parts so I will have to shop around and see what is what next time I am bin box diving.