Hey guys - Between a friend and myself, we have flown the Rascal 110 on these engines: SuperTigre G-2300, SuperTigre G-3750, FPE 1.3, Zenoah G-26, and a Moki 1.8 !!! Needless to say the Moki 1.8 provided some thrust offset challenges initially, but it would hover the best of all engines. The FPE 1.3 was underpowered for what we like, but probably provided the best scale like flight. The SuperTigre G-2300 was also a good selection, as was the Zenoah G-26. My buddy has the SuperTigre G-3750 at present and I haven't really seen it yet.
My point is that depending on what you want to accomplish with this plane, there is a large and varied selection of engines available.