Valve seat grinder

Don't try using anything other than a seat grinder to power the stones. High speed is the key and a common drill doesn't cut it. But you'll need pilots, a stone resurfacing tool, and multiple arbors if you are going to do something worthwhile. I have been down this road and have three arbors so you can fasten a bottom, face, and top cut stones to their own arbor, a selection of pilots, and a resurfacing tool. I think this would be a better choice for a start but that's just me.

Snap On Blue Point Valve Seat Grinder by Black & Decker | eBay