Trajan has similarities that you might find acceptable.

actually, many in that same vein but as you said, no exact match in my search either. i'd guess that the craftsman had a sample, but the cut probably does not match exactly. pre-digital too... maybe one of the more knowledgeable contributors can find a match in a specimen book.

This was the era where major architects developed their own lettering styles. The architect of the new MIT campus, William W. Bosworth, modelled this building after the Pantheon in Rome. I suspect that the inscription is his idea of an improved version of the Trajan column lettering, designed to be effective as a monumental incised design. Note that C and G have almost horizontal strokes on the right hand side. If I recall correctly this was not found in American typefaces of the day. But perhaps I missed something?
Don