Further update, I have managed to find a real 80 track disk drive and a working Bios 3.4 floppy disk, which is a feat in itself. When I say 'working', it hangs with the same symptoms we saw with the Gotek image previously (shown again below).
Code:
Gemini Multiboard Computer System
64K CP/M-80 vers 2.2 (Bios vers 3.4)
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I think it is probably time to take it all out of the rack, reassemble it in the case, and add the Xebec controller.