No -- I think I tried to contact the buyer (this was before they started using truncated buyer names), but didn't get any response.
Anyhow, I've completed the meat of my rewrite based on this thread. I'll probably edit it somewhat, but the argument will stay the same. Thanks so much for the idea that it may have been education-only -- it's definitely a possibility. I just paid way too much for four copies of MacWorld from 1987 (March, April, July, August) -- probably useless, but we'll see. Here it is:
Platinum 512Ke machines have a 1987 copyright date on the label. They came with the M0110A extended keyboard and contained second-revision Macintosh Plus ROMs. The location and design of the Apple logo on the front of the machine was the same as the Plus. These machines definitely existed, but I don't know if they were ever sold retail. They may have only been sold to educational institutions. At the time, Apple considered System 3.2 Finder 5.3 to be the maximum for machines with 512K of RAM. [it was only later that Apple would start recommending System 4.1 Finder 5.4 as the maximum.] This fact probably explains why no effort was made to update the owner's guide and software bundle in 1987, and it might well also explain why the machines might have only been sold within the education market -- Apple considered them to be obsolete!
QUESTION: Do you or anyone else remember exactly where it is in 1987 that Apple says System 3.2 Finder 5.3 is the maximum for 512K machines? I'm absolutely certain they do, but I can't recall where.