There is no such thing as an "engine I would never use agine". The bottom line here is you don't know what you will be using several airplanes down the line and most people do not. Even with careful planning things change.

Do yourself a favor like jester suggested get the appropriate engine for your traner. And that should be a good quality .61 such as TT61Pro or OS61AX, you will not regrete that decision. Indeed stay away from four strokes for now.

John