The kit sprocket will not fit those nice 60 spoke wheels. There was a time when you could order Micargis with 36 or 60 spoke wheels. Check on it.
You may be able to put a Huasheng 49cc 4 stroke in the frame. To me, it is easier to mod a four stroke mounting plate than fab a custom China girl mount. You may be able to modify a "Stingray Chopper" mount from ebay to attach the China Girl.
-If you are willing to do a friction drive engine kit, the 60 spoke wheels will not pose any problem.