Just to add another thought here, the G20/23 had a reputation for a touchy carb, especially with the pattern guys who like to use the throttle. Mid-range was not too terrific. Various fixes are out there, but one of the best was to replace the carb with the Perry carb and probably also the pump. I last looked into this a couple years back and they were still available, just have not pulled the trigger on it yet as I have no plane for this motor.
Hope this helps someone out.