When you change a distributor or its drive gear, it is essential you set the proper end-play. If you don't it and the drive pin is subject to higher than design forces.
Going to a larger drive pin is just a mask for an improperly located drive gear. That is the reason they come to you un-drilled, with a pilot hole. If installed properly, all the forces of the gear and camshaft are absorbed by the boss in the block, not by the drive pin.
Here is a link to the Ford bulletin:
Distributor gear installation
Paul