Jim's Steaks, here in Philly uses "Top of the Round" only.
You gotta order it right, too. "Whiz wit" or "Whiz witout" (onions)
You can order provolone as well.
I like both, but if I make them, I like provolone, and for heaven's sake, do NOT use steak-ums or anything that says "Same as a Philly Cheese Steak".
I'd rather have a bad day hunting than a good day working!