I emailed the person whose name is on the printout, and he replied and told me that he custom-built the prototype and wrote the code himself, but was hesitant to send me any of the missing files.
That's odd, American engineers dating *that* far back tend to be fairly forthcoming with information - compared to their corresponding Japanese analogues, at least.
Oh well, the fact that you homebrewed up a "replacement" is still heroic.
PS. Your homebrew remake can possibly be preserved in MAME too, guidelines regarding non-arcades tends to be looser. See the 4004 Nixie Clock as an example.