Somewhere in the early to mid-70's, gold emblems started showing up on guns other than the Python, New Frontier and Gold Cup. If the trooper in question is the original made in 1969 and earlier, then the stocks were probably changed in its 40 plus history.
Most likely they were just swapped out somewhere along its life. They came from the factory with silver. I agree that now ..original silver target stocks are the hardest to find. And it may be because people are swapping them for gold to sell as python stocks because of the prices they are bringing.