RE: World Models, a Chipmunk, and a choice
Any .90 4 cycles will pull the Chipmunk well.
I have one from WM and flew it first with Thunder Tiger .61 and now MDS .68.
Better now. Very good simple aerobatic model ( no 3D). MDS after 2 gls of fuel running smooth and powereful. Prop 13x6 or 12x6.