You want a true roll pin .It looks like sheet metal rolled up ( many layers) the pins that are one layer are spring pins. MSD handles roll pins . I bought five at a time. I Got tired of looking around. More than likely you tested that pin prevoiusly ,like a cold start and it didn't completely break then . I can shear my pin when cold if I use too much throttle when
oil is still cold. If you enlarge the hole for a larger pin you weaken the shaft it's self. Look at it as a built in safety. Guys go to larger pins and something stoppes the
oil pump .trhe engine continues to run twisting the drive shaft up. next thing the bearings are in trouble. Ask Brent mills. As it is aa original pin shears . the engine quits running instantly. Less if any damage that way. It takes about an hour for me to remove the distributor replace the pin ,get the engine with #1 up on tdc compression stroke. . set the distributor get a timing light and set perscicely. I was warned when I bought this car by the previous owner to let the
oil warm up to a minimum of 140° before getting carried away with the throttle. The thing to worry about is that broken little piece of pin that is in the pan now. That is what magnetic pan plugs are for I guess.