I don't know about off center MPC diesel wheels. I have seen wheels that had flash or parting seams that needed to be cleaned up (under the traction tire).
Back in the day, there were a couple of outfits that were providing a service to upgrade MPC diesels to magnetraction.
I never had it done, so I don't know what it cost. I am positive that the Railroad Shop in Endicott, NY did them, and I think Madison Hardware did as well.