You won't get anything that looks too scale with an os engine. If you really really want to have something closer to scale, you have only three choices. From least expensive to most expensive, the choices are:

1, a static prop when not flying.

2, an RCV 60SP engine which is internally geared 2:1 and will turn a 13.4x13x5 three blade prop.

3, go electric with a motor/battery combo with enough torque and RPM to match your desired prop. I don't know electric motors and batteries to recommend a specific combo.

Scott