I want to switch my saito into an inverted mounted position on my plane and whats the easiest way to attack this? Knowing that the thrust line has to be in line with the Crank shaft; how would one go ahead and make sure everything is lined up to accurately drill the new holes in the firewall.

Ive never did before in my modeling career but, to get this cowl and exhaust to work out the way i want it the motor needs to be inverted. Plus once i get my new YS for it I would have to mount it inverted anyway.