Actually most of the guys with the inverted engines start them with the plane inverted and then carefully turn the plane right side up. 4 strokes aren't bothered as much by inverted running. If I had a plane that needed an inverted engine I would look at one of those. Meantime I just stick to planes that have upright or sideways mounting. I agree with breaking in the engine on the plane. The break in period may help you catch other problems with the plane if there any. I was assisting a new guy to break in his engine when we lost control of the throttle. I pinched the fuel line to kill the engine so we could check the problem. The servo tray wasn't glued in properly and it had vibrated loose! Nice to find the problem before the plane took off.