this setup might be just what you need:
http://www.caswellplating.com/buffs/grinderadapter.html
this adapter coupled to a electric buffer like this
http://www.dewalt.com/us/products/to...?productID=174
this setup with 8" or 10" wheels will get you in the 6000-7000sfpm range. it should have a good amount of torque, being rated at 8.0 amps and 1400 watts, to get the job done. also with this setup you can use all standard wheels and greaseless or standard compounds. i use something like this most all the time but with smaller wheels and faster speed. as mentioned though be careful of the wheel grabbing and also if you go this route be sure to cover the adapter with duct tape to keep from dinging the work if it does grab.