I have a world models Cub-48. It has a 71 inch wing span and calls for a 40 size 2 stroke engine. I have an OS 40 FP and an OS 46 FX. Which of these engines would be the best choice for this plane. The FP is alot lighter and smaller than the FX. All up weight should be around 5 1/2 to 6 pounds.

Rick