[EricH]

It's a 4-bolt pattern. You just can't see the 4th one.

You could probably get away with not modifying the sprocket, but you'll need longer standoffs. The bigger hole would be to allow the hub to get through the sprocket.

330 did something similar for sprocket attachment, except that the sprocket was attached using the AM/IFI hole pattern (6 holes) put in the adapter, which replaced the stock hub attachment.