You shouldn't have any problems running the engine inverted. The only problem I ever ran into with an inverted engine was that the fuel tank was higher than the carb which caused a little more flooding than normal. But it wasnt enough to cause any problems and it can be fixed by just running the fuel line up and then back down to the carb, this helps by making the fuel fight gravity to get to the carb rather than just flowing straight down to it with gravity. Other then that tune the engine as normal. Dont listen to anyone who says it will run better with an onboard starter, all that is, is a crutch. A properly tuned Saito will run flawlessly in any position. Only use a onboard starter if it makes it easier to start the plane, which its intended for.