Inverted 2 strokes are no problem at all. If your model was designed for an inverted engine then the tank height should be very close to what's needed (centre of the tank level with the centre of the carb). The idle mixture has to be set so that it's very close to being exact, you can't get away with it being near enough (but we all try to set them exact don't we? ). Apart from that you'll need to develop a different technique for priming, after all, you're now trying to get the fuel to run uphill from the carb. Before you hit it with the electric starter always flip the prop a couple of times by hand to make sure it doesn't have a hydraulic lock.