RE: GP Waco?
FWIW, I've flown the Top Flite Cessna 182 with a Magnum 91; this plane is in the 11-12lb range. I thought it would be a dog, but the 91 flew it nicely. This Waco will be slightly heavier, with a lot more drag, so the 91 might be marginal. The Cessna would loop from level flight, but was not over-powered by any stretch. We were also flying it on 30% heli fuel, so take it for what its worth...