After quite a period of unrequited longing, I finally got an IBM Model F 107-key bank terminal (thanks, orihalcon!).
It was ugly and embarrassing, but I had said that if I ever got a metal keyboard, then I would finish it as metal!
So I stripped it and took it to the metal shop (auto renovation specialists) and asked them to shot blast it.
Assuming that it was aluminum, I was hoping for a nice gray textured finish, which I would anodize or otherwise preserve as true metal.
They worked on it for quite a while, but were never able to achieve a good result. Apparently, rather than good aluminum or alloy, the 4704 cases are made of what my father used to call "pot metal" - some bastard combination of aluminum, zinc, tin, and/or whatever else was handy, tossed into the smelting bucket.
So I got a blotchy, uneven surface with a nice texture but awful mottled color. Bitter disappointment.
So, I will use aluminum primer and paint it, the thing that I was hoping to avoid. The good news is that Rustoleum has a really nice line of "hammered metal" paints that will allow me to get a good color and texture, if "artificial" in that it is a paint.
At any rate, the keyboard is awesome and I will post a photo log when I finish.