Garret,
Imo a set of light Walnut rounded "Radius" (thanks GunRelics great descriptive word)
Would be more correct on a non magnum K target sight gun from around 1967-68 .
I love comparing SW diamond stocks and they had a neat evolution of changes over the years,
While there are no hard rules with anything SW, in my head besides the change in the checkering "Radius" and type of wood and it's color, the football cut which IIRC appears with the introduction of the Combat Magnum in 1956 does seem to be smaller in the beginning then get larger but again that's not a rule.
Woud love to have witnessed them being made , While I'm no woodworker I'm imagining some sort of spinning round router type tool carved it out and by driving that tool deeper the football cut gets larger but again that's just in my minds eye.
There was a very comprehensive thread on the evolution of SW stocks a while back, maybe someone can share a link.
My early 60's Model 19 target stocks look like the late 50's stocks, darker walnut and darker GA or Rosewood,
In the mid 1960's the Walnut gets lighter but you see mostly GA on post 1966 Model 19-2's with a lighter caramel coloring ( again no absolutes here just generalities).
The deep SS escutcheons go away with the diamond center, Iirc there is a brief use of a shallower SS escutcheon then a change to a shallow brass escutcheon in the late 60's (68-69?) But brass is standard by 1970 although the GA wood is still nice, this changes sometime in the mid 70's to a lighter orange colored wood although my suspicion is they used what was on top of the wood pile that day and perhaps as the supply dwindled they might dip into a vein of older darker GA, but just guessing here.
Ps, usually people sand or steel wool stocks before refinishing them, when this is done it removes the sharper more pronounce edges especially on the football cut, even more so when removing shallow imperfections/shell dings etc.