kmot, I have flown quarter scale Concept Models kit Fleet biplane with magnum XL400 radial.
The airframe designed for 120 4st motor, so this engine make the plane too nose heavy.
I have to mount servos, receiver and battery in very tail end to balance properly.
The engine run very well, got 7000rpm with 22x8 menz wood prop, tick over 900rpm without plug heat.
It start at first flip every time. no miss on all cylinders entire flight.
It fly very well also, however I have stopped to use the engine after several flights because I do not want to have structure failure (weight of the engine is more than double and over power)

Hope this help you....Koji