The only issue I have ever had with inverted engines be it 2C or 4C is the first start, the fuel will not feed properly as I always flip start. For me I find that the engine has to be tuned patiently and after that there are no real problems at all. For the Chipmunk go for inverted, the cowl will allow the engine to be partially hidden. I just got my WM one up and it has an ST G90 ... over powered, I might look for a 90 sized 4C.