Re: New guy...acquired a bike that is screaming for a motor
Welcome to the forum, Jim.
That is an interesting project and with some work and ingenuity it could be motorized. As for legality, you're right. 49cc seems to be the limit in most states to qualify as a motor assisted bicycle. nevertheless, as you said, flying under the eye of the law is possible, but not advisable.
One other thing you should consider. Any custom motor mounts that will need to be welded to the frame will require a person competent is welding aluminum. It seems unfortunate , to me, that the builder elected to mount the crank where he did. It's right in the place the engine should go. Not a project killer, but it does offer some hurdles.
Good luck. Let us know what you do with this project.
Age and Treachery Will Always Triumph
Over Youth and Skill & "Charlie Don't Ride"