In the O.E.s' (and as in many aftermarket units) original manufacturing process the drilling for the roll-pin was an arbitrary endeavor in placement, therefore provides no specific reference as to the the proper gear placement.
As far as the just turning of the shaft to pick ones' own drilling, as is most often practiced, we prefer and practice the process of removing the original gear, then with a jig we created, compatible with a drill press, to locate the original path of the previous drilling both in length, rotation and center (as often the hole does not pass thru the center of the shaft), press the gear to the proper position, and then place back in our jig thereby requiring drilling only the gear and engaging the original hole presented thru the shaft. This preserving the shaft for future gear changes.
And yes, I have witnessed the shafts breaking at the cross of the otherwise accomplished multiple holes drilled; this in one instance, the shaft separated at the drillings, oil pressure lost, the technician removed the distributor and saw nothing wrong, the entire shaft turn together by hand but under the pump load the separated lower section remain stationary only being located in the gear.
Scott.