I know of two shops here in Pittsburgh, PA. I'm not aware of any in Illinois. I take it you are doing an all origional restoration. If so what year car? You probably already know, but depending on the year you could be dealing with a generator and not an alternator.
Actually looking for someone to correctly restore a date correct alternator that came with a 69 camaro that I show. Looking for another 10-15 points in my quest for a Gold spinner at the upcoming Chevy vettefest in Chicago.
Found this guy in Hemmings that will restore and correctly finish/plate my alternator for $190 plus freight. He can be contacted at kenbrunomotorsports.com. He does alot of Corvette restorsations where things such as correctly dated diodes are critical.