I think this might be possible. It's not just grinding though. There is a raised rim on the front side of the single plate hub. I don't know if that is needed for proper function - but it might be for added strength.  Here is a picture of a new hub for single-plate, along with a used hub for dual plate. Sorry the pic doesn't show the raised rim very well. I'll dig them out of the box again for another pic if somebody is serious about trying this - and I would loan my new single plate h