I was away for two weeks in Greenland and Iceland for the recent eclipse. But I'm back and still interested in moving forward with this project.

I just ordered five AM29705 and five 74LS172's off eBay for reasonable prices. While that's enough AM29705's for a 16-bit machine, I would need three more 74LS172's. But I figure I will try both chips in my four-bit breadboard prototype to get a feel for them.

The DARK SIDE Whispers go 20 bits.
Try out a few designs 16 and 20 bits wide. Memory is cheap, pennies per K not like the 1970's when it was dollars per byte.