RE: Balsa USA Fly Baby Biplane kit available
Horsepower is no reason to pick an engine. You have to compare the RPM on the same prop on each engine.
If 2 engines turn the same exact prop at the exact same RPM, they have the same "power".
If one turns the prop lower RPM, it has less power.
My FBB with a Zenoah G-38 is plenty maneuverable for me.