Call West Photo and National Camera Exchange (the downtown pro store, not a suburban branch) and ask to speak with their pro reps. Ask the rep who's doing the best C-41 in town that still does 120 and 4x5. They should know because they'd still be selling any 120 that pros are shooting and have some idea about labs. I'd go in town before shipping halfway across the country. Mpls - St. Paul should still have enough going to have at least one good lab doing C-41, although runs may be spaced out a few days. (National put a huge 3-4 mm wide scar across the C-41 4x5 negative of my brother's wedding photo (1981 or so) that went across his face and his bride's, so don't use their in-house lab if they still have one.)
If you don't get anything from West or National, shoot me a PM and I'll put you in touch with some local commercial studios that might have an ear to the ground.