Raimey;
I have only had the lock plates off once since I had it & that was probably around 40 years ago. I simply do not recall now if the top of the plate actually bends inward or if it was just thick enough to be beveled at the top.

As can be seen in the top view over some 120+ years the wood has likely shrunk a bit leaving the plate a bit proud at the top.

Looking at the two guns though it would seem quite obvious to me that the Spalding in question was indeed made by Clabrough.

Miller/TN
I Didn't Say Everything I Said, Yogi Berra