Update: It's out of Dad's basement, and on my trailer coming home! Strapped it to an old hand truck, dragged it up the stairs. Weighs a ton...
Gave it a slightly better "inspection" (looking for ID tags). There's a second cast label on the base, opposite the one that says H LEACH MACH CO. The second tag says PROV RI USA NO 60.
So, I think it's a Langelier 60, tagged as a Leach.
It also has a tag that says UOC with a stamped number. I think that's an asset ID tag from Universal Optical Company (where my grandfather worked, as noted earlier in the thread).
Some of the holes in the arc of shame are all the way through the table, sadly. The belt is very, very crunchy, and there's a bunch of grease behind the quill.
Didn't find anything on the (HUGE) motor yet, and didn't get a good pic of the power switch, but that looks pretty modern, and says Square D Company on the face. No idea if that switch was original or was retrofitted.
This thing weighs a ton. I have no idea how my grandfather got this down to the basement, but it looks like he put it onto a piece of plywood on the floor, and left it there for a few decades...
Mike