Bring back the Walker... :roflmao:
You should base it around a 68030 that was totally compatible with 68000, plus you can play more cpu intensive games e.g. 3D FPS.
What are your qualifications? I did 2 years of Electronic technician certificate, but there was no design subjects. If I did the diploma course you got to build a Z80 computer.
Considering all the cheap and nasty downloadable games you can get... If you can build the hardware someone will get around updated all the classic games.