Bill, I bought ones from Gunparts (Numrich) and the length was 1.408, head thickness was .090. The only thing I don't like is that the whole thing is threaded.
The measurements I have taken for the lock plate connecting screw is 8-32 thrds, OAL. 1.375, head dia. .222, thickness of head.060. and slot .031. In the trigger plate to tang the only difference was in the thickness of the head .070. That is what I measured on a 1928 Specialty Grade 12 ga.
I replaced a stock of a 16 ga. Field Grade I had gotten with a Hunter One-Trigger and ejectors, newer stock was from an Ideal grade 16 ga. After fitting for the Hunter trigger and putting sideplates on the original connecting screw was short by 3 threads or so. Luckily I had another that was longer, trigger plate to safety, just had to file the head down to be even with the sideplate.
I know the Gunparts one will work, but I would rather have an original style than an all threaded one.