Ted C. HowardSo, it looks like I can fit the “core system” (CPU, RAM, ROM, address decoding) on one standard size #Z50Bus card.
I like this one with built in power and reset
https://www.tindie.com/products/tindiescx/sc513-modular-backplane-kit-for-z50bus/
So, after looking at backplane kits on Tindie, I think one designed for the #Z50Bus will work. If I remove all the Z80 specific pins that don't have 6502 equivalents, that leave enough room for all my IO_SELECT signals.
