Should I make the swap to G3?

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).

Yeah, me being cheap as well is another reason I've built most of the stuff myself, lol. The wiring harness is actually one of the few times I pretty much just clicked the buy button without thinking about it too much. All told I probably spent $300-400 building my harness from scratch, though that was with some extra parts in case I messed up and I kept having to pay shipping every time I forgot something and had to make another order. Doesn't help that a lot of connector parts are on backorder everywhere, so that was another reason I didn't hesitate too long to pull the trigger.

I've nicknamed my car Frankendart or the junkyard dog. At last count I think I had parts from at least 13 different vehicles on it. And when I say different I mean totally different models, not just different years of the same thing. That really is half the fun to me though. I just look at the car and figure out what I can do next with what I have. I think my next plan is going to be getting the knock sensors hooked up to the new computer, but the module is currently out of stock.