RE: Mounting Saito 100
I've had a Saito 100 mounted in a Hanger 9 P-40 and a Super Chipmunk. In the P-40 I mounted it inverted and in the Chipmunk I had it mounted 90°. It ran great in either position. I'd go ahead and mount it inverted if it will fit in the cowl. The only consideration would be to the position of the fuel tank. You will want to get the centerline of the tank as close to level with the carburateur as you can, if it is mounted above the carb it will more than likely tend to flood the engine as well as siphon fuel out of the tank when the engine isn't' running.
Hope this helps
Ken