I have some serious doubts as to that 458 being a Shelhamer stock. (yes, it is one L and one M)
As for your rifle, that is a beautiful rifle and terrific stock, but I see nothing Shelhamer about the cheek piece. G&H used that style for a while, and Linden did some like that, but not so much Shelhamer. Not that he didn't make some with a similar style, but none of the dozen or so that have been in my gun rack have that style.
Shelhamers post-war work became very cookie cutter with very little variation in style. I personally think his pre-war work was some of his best work and had a more traditional classic style. There was more variation to his pre-war work as well since he was working for Neidner and had to do whatever job came in the door. His post-war cheek piece was not the most elegant thing ever put on a rifle stock, but I think at the time a lot of gunsmiths were struggling to make a elegant stock to fit the new fangled scopes that everyone was using. Shelhamer Stock
A quick Google search will find many examples of his work.
One quick way to help identify a Shelhamer stock is by the screw on the bottom of the forend. He nearly always put a screw up through the bottom of the forend into the barrel, and this screw always had a little brass aschutzen.
I believe I have only seen one stock that I felt was his work that did not have this feature. The uncheckered strip down the bottom of the forend, the border around the checkering, and the schnabel are also very typical of his work.
Love your work Timan.