You can run a motobecane variator on a pug crank with no work or special parts. Use one of the stock variator bushings and then impact the variator on. Depending on the variator, you may need a large thick washer or the little cup washer/spacer that sits between the rear variator plate and the clutch ball plate. You put that between the back of the variator and the little stub face on the crank and then impact it.
I've revved up to 12k with a mbk giraudo with no issue/no slip.
Using this general method, I have put all sorts of variators on. Scooter, derbi, etc.