[quoteDo you know of any of the current reprint Mauser catalogs that shows this option?

AFAIK the old Mauser catalogs don't show these pads in pics. They just mention "Weichgummikolbenkappe" = "soft rubber butt pads" among the special order factory options. Jon Speed's books show photos of several Jostam recoil pads on original Mausers. Not only the "Anti-Flinch", but their "Hy-Gun", "Air Cushion" and "No-Kick" models as well.
Note, I did not write "certainly factory original". It may be factory original or a contemporary aftermarket add on. At least, it is much more "period" than the American open sights, the Weaver scope mounts, the altered bolt handle, the low safety. So it is the last item I would bother to change.