Actually, I and many other at my field have had problems with inverted 2C engines. It has got to do with starting but also with tuning. We found that it would rich at full tank and lean out as you go through the tank. On a 3D airplane, this was an issue.

Apparently others had the same problem. I couldnt keep that engine running at all. When I finally gave up, one of the more experienced members came up to me and told that he had the same issue with the same airplane. So much so that he does not buy airplanes with inverted engines. He takes them if the engine is at 45 or 90 Deg

Ameyam