You're doing something more people should do...bench run your engine to get it set...then...put it on the plane

For fuel, 10% nitro 20% lube is just fine, pop an OS #8 (or A3) in the head and strap an APC 11x4 up front...bingo...there you have it. Your plane will do just fine with that combo...plenty of thrust, yet a lower top speed...just what you need for a trainer.