I just got a #2 rolling block that was rebored to 32 Ideal by the stevens company. The firing pin retainer looks nothing like any other retainer I have witnessed on a rolling block. It is like they used a rotating extractor to interface with a large headed firing pin retainer that would extract the firing pin. This is not like the #1 actions that had a firing pin extractor inside the breech block. This is on the side of the breech block where a later rotary extractor would go. This gun also has an inline extractor and does not appear to have been a rotary extractor gun.

Was this something Remington did? Or something Stevens did?

If know one has any idea I will posts pictures later. 

The ring like piece that retains the firing pin holder has an ear which pulls the linear extractor back. I have one like it. Are you missing the rotary piece?

Like Frank de Hass said, you have a perfect pattern for the firing pin. The hole. The rifle I have was a true piece of junk when I bought it. The barrel was set back and threaded with V threads and the wrist of the stock was wrapped with leather nailed in place. I junked all but the action and butt plate. I've cleaned on the action some. The firing pin was probably made from a nail so I made one and the cylinder that retains it. The new pin is not finished so any measurements I give you would be meaningless. A good material from which to make the pin would be the shank end of the drill bit used to clean out and measure the diameter of the hole. It will not be as hard as the cutting end but still tough. Good luck.