glass or alox will be fine. dont go too nuts on the grit size though. something around a 70 grit will get you a .5 mil profile and clean out any rust pit holes and still retain whats left of your numbers. Be mindful that there is no media stuck in the 4 parts of the face that sit against the outer ring. lots of wheels have a sealer there that can cause issues with media being stuck in there after blasting.