Ole Miss would probably beat the Trojans right now.
No doubt. I would still think the upside of so cal in the Pac-12 is better than that of Ole Miss in the SEC though. Kiffin might just at some point get Ole MIss to an SECC game, but that's a tall order with bammer in the way, also Texas A&M and LSU if they ditch Ogeron
He has a much better path with so cal. There are a couple other traditionally good programs (Washington and more recently Oregon), but so cal has the third most NCs in the NCAA after Notre Dame and bammer. It's still a much more attractive destination than Oxford, IMO.
Having said that, so cal would have to be crazy to bring Kiffin back. He has too much baggage IMO.
I guess crazier things have happened though.