To narrow the bearings, I use a modified connecting rod where the back side of an old rod has a round extension welded to it so the rod can be placed in a lathe.  The small end of the rod is simply cut off to get it out of the way.  The rod cap itself can be removed while on the fixture and in the lathe.  With the bearing installed in the fixture, I’m able to machine the edge of the bearing to the desired width.  While in the rod fixture, I put a slight chamfer on the journal edge of the bearing.  Keep in mind that once the bearings are narrowed, it’s important to keep the upper and lower halves marked accordingly.