So, I would say that we now have a credible, manufacturable design for the Sentinel 65X. Doubtless there will be many little refinements as it grows into a real product, but the core design seems to have settled into a form that is practical to build.
So the next steps are to design the developer harness for the clock port which @swetland proposes to make, and to design the Rev0 PCB, and to have a small test batch made.
This is where I begin to get neurotic about the whole thing.