68008 Main board Review
A few comments:

Don't use data strobe on your data buffers.

RAM/ROM CE and WE should use data strobe (ANDed with other signals). Otherwise, spurious writes will occur during signal transitions.

Your I/O connector should have a lot more grounds. I recommend 20%.

Do you have a plan to get it up and running? The 68008 doesn't have a test port, I always had a hardware emulator available to help with this. 

Grounding, clocks, and sneak paths, these are the things that have bitten me the most in my career. Your clock is point-to-point, that is good, but consider a series terminator. All your circuits are on the same Vcc, sneak paths shouldn't be a concern. Use ground planes and lots of grounds in connectors.