That is not a run of the mill stamping. In 1971 there would have been very little stamped on the upper pad, usually just WT for Water tested, and other small letters and numbers indicating machining details. Also, if the color is true in that pic, the paint looks to be of 1968 and the earlier "Race Hemi Orange". It makes me wonder if it's an earlier engine with day two stampings on the pad added by someone (machine shop etc.). Another possibility is a warranty replacement engine which sometimes had unusual markings on the pad. At any rate, if you want to really know the answer you'll need to look at the VIN pad on the forward lower side of the passenger side on the block.

Typical Hemi Vin stamping