Zorro expansion was always meant to be 100-pin. So your Zorro I backplane expansion is the same as the Zorro II backplane of the A2000.
The 86-pin edge connector was a quick and dirty cost reduction effort that can be brought back out into the full 100-pin bus.
The card bay and slot layout likely looks odd becuse the early standard for Zorro had the cards in a different form-facor than the A2000 eventually got.
To see what Zorro was originaly meant to look like, check out a BytebyByte PAL expansion chasis. It's a clone of the original miga design AFAIK.
