swap grubbee out for mitsubishi

I have a Greenline 7spd beach cruiser w/a sick bikes jackshaft kit and a standard 66cc Grubbee. I have thought about trying to remove the Grubbee and install a Mitsubishi 43cc 2 stroke that I was using as a friction drive on another bike. Has anyone out there done anything like this? Results, any tips? Thanks in advance

 

[KCvale]

Chance are slim to none that the back of the other engine would attach to the JS housing and something is needed or the JS housing will twist on the seat post.