I'm thinking about getting another motobecane, I loved that bike so much even as a regular pedal bike it was the nicest bike I've ever owned.
I'd probably do another gebe wheel/custom motor mount, but with a bigger displacement engine and geared for more torque.
V1 had a 27cc I built from the ground up and a 14t pinion cog. V2 will have my ported/piped 43cc and an 11/12 t pinion with a belt tensioner that helps the belt contact mor of the pinion cog "that V1 lacked" so it can climb better than my axle mount setup. It has a 5:1 trans, 11:44 gearing, for an actual 20:1 final drive ratio.
The gebe sheave has a virtual tooth count of two seventy something? I can't remember?
I'll go do my gearing calculations and start saving for a $800+ motobecane and a $200 velocity wheel.
LOL I still have my FD mount that I started with " modified for belt drive " I could use that, but its crude even by my standards.