Guillow's does not have recomendation for R/C conversion for this plane that I know of. Their included recomendation for free flight is for .049. For control line from .049-.15 engines.
Indeed some have been successfully converted to R/C but all I have seen were electric conversions.

I personally would not put an internal cobustion engine in this model larger than a Norvel .074 but that is just me. I have a feeling it would not be an enjoyable flying experiance for most people with a .10 or larger engine unless it were made Ucontrol.

Check out this thread for a video of an R/C Guillow's Skyhawk. Beautiful model and wonderful flying. It comes in at 10 ounces. If you can keep the all up weight at 10 ounces or under, even with a .10 you could very well have a winner.
http://www.rcgroups.com/forums/showt...hlight=Skyhawk

Just my two cents, Robert