I always thought a straight bar hard tail mountain bike frame with a monark style stringer front end, no rise pull back bars like the Nitto B617 Promenade with bar end levers, and some 24" Thick Bricks would make a great looking motorized bicycle.
I have a 1993 KHS that I plan on doing something similar with, but electric and starting with a regular mountain bike fork...
Good luck with the sale! I figure it would be pretty easy to move that bike on CL when the new semester starts at Texas State, probably. Also, try both the San Marcos and Austin CLs, the Austin one gets a lot more traffic.