I use inverted mounts with TT .46 Pros & generally I have no problems with the engines, once they are running. I have had problems with flick-starting, but never with an electric starter. Try & mount the tank as low as possible in the AC. The TOP of the tank should not be higher than the carb, if you can avoid it.

An inverted configuration that helps is "3/4" inverted, rather than fully inverted ( the engine is rotated 135 deg down from the normal upright set-up). This puts the muffler directly under the crankshaft & down the centreline of the plane. The carb is thus positioned somewhat higher in the airframe than in the fully fully inverted case. It also minimizes the bits that stick out of the cowling.