On the chance you still have this cab, how is your RS422/RS232 board wired to the Naomi? Could you grab some pictures if possible?
I'm trying to run this emulator on my own DOC machine and I'm getting "card reader does not respond". Stumped a few people as it's all wired exactly like your post.
For anyone who may use this emulator for Derby Owners Club (a few people), I have made some reproduction cards to use for card images. Access here.
I would just attach the .zip but the site doesn't want to let me. Probably because my account is new as-of writing.
These are pixel perfect (or...