Welcome to the forum!
Your in the right place, this forum is a treasury of information.
The Morini engines are nice, but a little out of most people price range, plus you have to custom make and weld/bolt mounts for the motor.
The only reason I have a boxer with a Morini is because I bought it locally on craigslist for a very reasonable price! Theirs I nothing like a full suspension motorized bicycle.