The little 18cc weedeater engines just don't put out enough power for their weight. One might work ok on a floater plane like a small cub that flies on the wing instead of raw power. The choices you outlined are aerobatic planes and you would be very unhappy with the performance. The larger 23cc and up engines are a minimum for what you seem to be looking for in a project.

Hope this helps,
AV8TOR