The only OEM walnut stocks for the Winchester 70 WSSM are the featherweight style. A while back, CDNN was selling the leftover Winchester/USRA stocks, but the last time that I looked, they only had a couple of laminated WSSM options left.
Since all of the 70 WSSM Featherweights, Super Shadows, and Ultimate Shadows have the same barrel length, 22", and contour, I think that a number of people swapped their synthetic stocks for the walnut featherweight stocks.
Good luck with your search.