I like the idea of two separate boards, a common G8PP memory/IO/CF board, and a CPU board.  I've designed 5 CPU boards with that concept in mind.  These CPU boards have male RC2014 connector on one side and female RC2014 connector on the other side so the common G8PP board can plug into the female connector resulting in a complete computer without a RC2014 backplane.  Below is the picture of such G8PP & Z80 combination.  All the software from previous project work on this new configuration.

I've spent quite a bit of time on Z80 to develop the G8PP concept.  I'll now move more quickly over other 8-bit and 16-bit processors.  Below are pictures of G8PP+CPU for 6502, 8085, 68008, and 6809.