Rob,
Your post indicates that this fellow is going to build a trainer before he ever flies the Cub. I personally would build the Cub, not run the engine at all, and let him hang it up with the engine still brand new. The Cub is not an easy plane to takeoff or land and IMO requires somewhat more skill than a beginner or someone who hasn't flown in many years possesses.
Built it, don't run the engine, let him hang it up and admire it, and when he is ready, take it down, break it in and let him fly the wings off it.

Regards,
doubledee