I'm Heartbroken. Time to face reality that my Cuda is a parts car.

You, yourself said "find a cheap more door". That's how I saved a 68 vert for a friend/customer. When the serious rust was out, it was literally gutted like a fish. Firewall back to tail panel, rocker to rocker. Can be done. Patience, don't think it has to be done tomorrow. Vigilance, strike when the iron is hot on good deals for parts.
Lots of things to unpack here,lol
Obligatory "if you want to fix it, gimme half of what it's worth parting out, and it's yours!", lol
Patience... I waited 10 years to work on her.. kept her in the garage, kept the kids away.
I'm 53, and I've beat the hell out of my body in that time. Smoke too much, drink too much, don't eat right, etc..
My Pa died at 57. He had a '62 Ford Galaxie 500 ragtop he had been working on here and there for years.. it's rotting away in one of my brothers yards right now. I don't want that to be me.
I also have a 17 year old kid.. he's never ridden in a car with roll up windows. Much less an A-body with a stout 340 and and a rear with 4.10 gears.. I'd like to give him that time... maybe let him borrow it for senior prom. If it's a more-door Valiant that he smokes the Honda big wing guy with, that's even better to me than doing with a bright red cuda... I was always a 'sleeper' guy.