The plane needs a prop extension hub of about 1", quite easy and OK with MVVS. It puts the engine backwards and allows for a nearly fully concealed lay-out.
3.8 horses as advertised is real. For tractability, a two stroke never was quite the same as a 4-stroke. The faster throttle response of a 4-stroke makes the "feel" of the engine quite different. The 4-stroke does not need to clear it's lungs like a 2-stroke does. (crankcase fuel accumulation in nooks and crannys)