Is the CDC 6600 and it's successors an open source CPU? The way luke talks about the CDC 6600, it is totally available for inspection, unless you're looking for the more obscure parts where you just have to know someone.
If so, I'd be interested in finding out more. Experimenting with your own CPU using plain old off-the-shelf parts is rather interesting. Yes, I have heard of the youtube guy who made a CPU called Megaprocessor.
I often think that we lost a lot of genius due to the closed source nature of modern processors. Not to mention the methods of creating these CPU designs.
Concerning luke's need to drive 128 gates from 1. You could probably operate more gates at once if you used a MOSFET instead of a normal transistor for your driving gate (I have no idea if or how that would work in silicon though).
Thanks!