I think OS 25 up to OS 32 would be fine, If money no object OS 32, Its what Im putting in mine, YES I,m still building it many delays in my house remod. putting me behind, also working on my SIG SE with YS 63,

Good luck, Let us know how it turns out.

Dennis

Gotta love those 32SX engines! They use way less fuel than the 40FX, run much quiter and will spin a 10-6 prop as fast as the 40FX typically at 14,200 rpm!.