Just a thought, if its a special coating, don't let the machine shop remove it from the journals. Have them try on one of the cast areas first to identify it. A hardened surface can be ground. This sounds really far fetched, but it looks like a Tungsten Carbide coating that we spray on our turbine shafts. We then have it ground to final dimension leaving a very hard and smooth journal surface. In fact, its so hard that we have yet to replace a shaft due to catastophic bearing failure. Needs special grinding wheels though.