I think the Ford design is lacking on the pin? Most put a hardened pin ion and maybe the next size up?
Use the Spirol wound hardened pin that is used in the stock Ford distributors. Some aftermarket [Mallory] distributors use the cheap single wound mild steel pin and will shear. Do not drill to the next size, this will weaken the shaft. A little Lock-tite red on the gear/shaft will help too.