Those engines are a sight. Wow!
Full rich for take off and landing and initial climb—maybe 11 or 12:1. Then up to cruise, level flight and lean the engines to peak EGT, which is about where our bikes run most all the time. After peak EGT then either add fuel to drop the EGT 50 degrees for best power, or reduce fuel and EGT by about 50 degrees for best economy. Interestingly the only place the engine is not run is PEAK EGT! It's too hot and bad for the engine, yet it is where our bikes are set up because it is the point of lowest emissions when used with a cat.