Final follow-up:

Got the new carb on E-bay per Oldtimer2's advice. Shortened the brass axles for the carb and choke pivots, made new arms out of brass and silver-soldered them on and bolted it to the engine. Attached new linkage for the servo-operated choke and all is well. Too cold to fly in Kansas City this time of the year but I expect success when it warms up enough to go to the club field.

The old carb was a Zama C-1. The opening of the carb bore was bigger than the replacement I bought but the adaptor plate between the carb and the engine now match. The bigger carb was a bit fussy to tune and I wonder if that might have had anything to do with it?

Anyway, thanks to all that contributed to the solution to my problem. Good landings to all!