I believe this is the head code: 3836850 (I errantly stated, above, that it was cast into the manifold. That was/is incorrect. It is cast into the head, between the valve cover and the manifold.)
Removing the valve cover revealed the following, both cast into the head, on the driver side: "CON9" & a bit posterior to that "K 21 8"
I checked again, with better light, and still find nothing in the way of a serial number on the block. I can keep cleaning/wheeling and see if there is something on the far end, but it seems unlikely. Aside from my cleaning/wheeling/scraping it looks wholly unmolested. (See attached photograph.)
