Crosman 760 PowerMaster

I received my first air gun on Christmas of 1970 (maybe 69?). I remember it being a Crosman 760 PowerMaster (wood stock and forearm). I vividly remember it as being able to penetrate (BB) two clamped together NC car license plates.... the kind that would rust. A pellet would impact a blister the size of the end my thumb on the same target. I remember this gun having a pump maximum of 20 strokes in the manual. I understand that the inner pump of this early version was made of metal while newer models have plastic pumps.

Has anyone here ever upgraded a new version with a metal pump? I would be interested in the details.