Re: Has this been tried yet?
If you can find them, look for cog belt pulleys. Cogs won't slip unless the belt is worn or very loose. Timing belts on cars are a good example. Check Grainger for pulleys and belts.
The biggest hurdle will be the width of the belt compared with the space you have inside the clutch actuator cover. There are narrow belts but when you get that thin they might not take the abuse of the engine and have a short life span.
An option would be a jack shaft where the engine would drive the shaft by a short chain and the pully would drive the rear whel via a belt. Then you get into gear/pully size calculations.
Another alternative would be to not use the clutch, leaving it fully engaged and go with a centrifugal clutch adapted to the shaft where your sprocket is now. I've never seen a cog belt centrifugal clutch but they might be out there.
Good luck. Let us know if you come up with something.
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