If you want to risk an expensive engine several people fly with F2D motors(old ones) on6-6.5in. props, trimmed down, smaller venturi(don't know the size). This setup turns a bit tighter but has more trouble in the wind. The longer lines do make the plane more touchy so longer mounts or weight, or other trimming is needed.
The K&B 28 is a nicely built engine form MECOA. They'll build it up with a venturi and needle valve for C/L. Performance wise it is pretty much even with the OS engines, but an ounce heavier, so the plane either needs to be a bit bigger or some other adjustment.