A friend of mine that did quit a few ring & pinion set ups took a new pinion bearing to a machine shop and had it honed out for slip fit on the pinion shaft. We used this bearing for set ups. It made changing the pinion shim a non issue. Once the whole set up was dialed in, we took the pinion out and replaced the honed bearing with the press fit one.
This won't help you now, but it might save some set up time for someone down the road.
