Hey Randy, going by spec sheets, the CXS is listed at .51, and the FP at .41 hp. The CX has duel ball bearings, and ABC PC.
Maybe Andrew has run both, and can share the difference of power. I think it will be a perfect match for the ringmaster. Just need to find the right prop.
Andrew, does the engine have a broad needle range, ( doesn't run away, with rich settings)?