Yep, sounds like you are close to hitting all the bullet points. Nice job!
I totally missed that you had a T56 in your car. Hoping to pull the trigger on a 2.97/0.50 one in a couple of months.
To be clear, I am working on adding most of the things I mentioned to my car as well, minus the ABS as (right now) that seems like a real stretch. While not an ME, I am a Mechanical Engineering Tech (glorified drafter) and spend way too much time dreaming up ways to change things on most of the cars I own. I've laid out and built my own BBK, a custom pistol grip handle and played with a custom dash. My biggest problem is time though as it took me like 13 years (seriously, how dumb is that) to bolt the 13" brakes on my car. At that rate, I will be 35 years in the making to add the rest of the stuff. Add that I am too cheap for my own good resulting in spending time on retrofitting some OEM box for heat/AC instead of just springing for a kit.
Absolutely love the idea of modernizing these cars. Just wonder how Frankenstein mine will turn out (if I ever get it done).