Actually it's a great idea.

What engine does it recommend? I'm asking so we will know how much weight the airframe needs to balance.

I just put a 25cc Toro conversion on a 60 size Tiger moth biplane. It balanced perfect with no additional weight.

If the 38cc engine is to heavy you can shorten the nose. One inch means a lot.

The general rule is 1200 square inches for a gas conversion.

But the Space Walker is a slow flying plane that I believe could handle the weight.

By the way, you do know that 38cc engine is a real over kill.

Not that it matters any.