Hey Bill, came across this old post while googling for something unrelated and wanted to clear this up.
The 256K ROMs work fine with the REV F 8088 coprocessor cards. But you have to have -03 or -04 of the Kernal matched with the -05 PLA. And you should have at least -03 of the BASIC ROMs as well but that's not as important. The MSDOS and CP/M-85 bootstrap loaders are the issue and why the other levels matter.
I have two and they run just fine. The 256s have a more relevant coprocessor incompatibility, at least those with CEAG sourced power supplies. Those power supplies are 1/4 inch too deep and will make contact with the boards and short them out if you don't notice it! The General Instrument made power supplies are fine. Seems like the 128s all came with GI PSs but 256s can be either.