Recently picked up a Remington Hepburn action with breechblock modified as described in one of Grant's books.  A groove is cut vertically down the rear of the block in which is hung a lever pinned at the top and loose at the bottom.  The old firing pin channel is plugged and a straight line horizontal pin is fitted.  Front of block is bushed.  The hammer hits the bottom of the lever and the middle of the lever smacks the new firing pin. Very elegant, I had read of this but never seen it done.  Tangs have been shortened and stock bolt fitted.   
Does anyone know who originated this alteration or when?  I wish I could put a name to the gunsmith who thought it up.

Will have to learn how to use a digital camera.  in the meantime you might check out Grant's Single Shot Rifles, the first of his books, which I think is the one which described this alteration and may have had a photo of a rifle so altered, in the last chapter on customizing SS rifles, I can't get at my copy, apartment being painted. 

If there is anyone reading this who is talented enough to make drawings of this rig, I would be glad to send them the action, or maybe we have a good photog among our readers.

Dale, sent you an email.  Mark