My feeling on setting up the mounting plate with tight fitting (slip fit) retainers is, if the retainers help to locate the plate besides just having the tightness of the bolt alone being responsible to accomplish that, there will be far less of a chance of the plate working the bolts and loosening them. One could even add a couple of dowel pins to do that job once you have the gear clearances worked out. Setting up the dowels would be easier than the trial and error of doing it with the mounting bolts holes.
For anyone interested in doing what I did, I concentrated on working the lower two mounting bolt holes for the tight fit. The top two holes were left alone. A total of at least three of the holes will need to be tight fitting. I had one of the upper holes, which I did not have to work, and both lower holes, which I did have to work.