Why not look into the CVT to mount up to that engine. That way you get the best of both worlds for
<$75 for the CVT. You get the belt primary drive like the others AND the advantage of multiple
gear range from 7:1 (low) to 3.5:1 (high) primary! Do what you want with the secondary depending on
bike/rider weight, terrain, city or rural.
Just another (often overlooked) option. And no, I'm not a dealer, seller, vendor.