Hi
As I stated above the C 35 Combat will work in The a Stunt plane like a Nobler, It is a much better choice than the G-21 35 is, but, Also there are better engines out there for you to use.
Randy
PS I made a couple of G21-35s with single bypass sleeves, baffle pistons and the slotted ST 35 head, they ran OK, But had no where near the power of the HP-40 or the G21 46, and weigh as much