been curious about basically a '7100 dos ready' label on an untested unwanted rom simm
No 7100s were sold as DOS compatible machines and none of Apple's own aftermarket DOS compatibility cards targeted it. Although I believe that some of the DOS compatibility hardware is documented after-the-fact to work. (the 6100 DOS card in particular, once you work out how to make it physically fit.)
And, among Macs that were sold as DOS compatible and/or have affordances (e.g. 7200/120 DOS compatible or any 8500 or 5400 with a GIMO port), there weren't special ROMs to accommodate the card.
It's possible someone pulled the ROM simm out of, say, a 72
00/x DOS compat and then just decided it was a DOS compatible ROM, which isn't strictly true or sensical, sine the DOS card on the 7200 and 4400/7220 was just a PCI card that was preinstall/configured.