The Oriental is a decent stunter. It will fly with either motor, but my choice would be whichever is lighter. And that'd probably be the 2cycle. You've got a better chance locating the CG where it's needed with an engine that's closer to the weight of our originals. And back then, we didn't have carbs on 'em and if anyone was flying 4cycle (with it's appreciably heavier baggage) I never saw it. The 4cycle will have less power but that's not the point. Balancing the plane is the point.

As for ailerons..... They're actually flaps that work both directions. No big deal what they're called, but might as well lessen confusion when communicating. There really isn't a strong need to lock them in neutral. CL handles with adjustable spacing can do what you seem to want. On the other hand, if the instructions show suggested rigging for elevator only, your idea has a better chance of working well from the gitgo. And if the plans don't show any rigging for either setup, either way has equal chance. Just keep in mind that it's better to keep your handle line separation wider than narrower, and the same for all your planes, so rigging the plane takes precedence over re-rigging the handle.

It's a good flying plane and ought to work well.