Britton,
The Saito will be just fine. It is built in a 70 size case so is light for the displacement. As far as a "better" engine it is up to personal prefrerences. I had an OS 91 in mine. A friend had a YS-63 in his. Both planes flew well. In any case low end torque is what you want. The fuselage is a little weak from not having a lot of wood left after the wing cut out is done. Keep an eye on it.
EXCAP232