A 60 size plane in the 65" w/span range are able to just fly with a 60 sized 2C engine and would be fun with a 90 sized 2C, if you get a 108 2C it will be totally fun! Even with the 108 2C it is not totally overpowered yet. The wing loading would have gone up a bit but still manageable. What is most important is vibration (too much vibration will cause structural failure), fuselage integrity (wings ripping off, engine coming off the firewall) and over speeding (flutter, wings snapping off, stabs coming off).