captinjohn, you have my curiosity up wonder what you have in mind?
Also how much prop is normally used on 100 size engines, I thought 27x10
I cured that mid range being too rich by cutting the "moon" on the throttle plate a few thousands larger. If you cut too much out....the engine will continues to run with throttle closed. Best to research it to see how it is done. All it take is a slight touch....