I have no Idea where to start

What "I" would do is pull the engine and install a 360... 408 crate engine. While the engine is out I would convert it to manual steering. Power steering is OK but robs horsepower, leaky, has to run another belt. Paint the engine bay the same color as the car. To me this is where the previous owner stopped working on the car. He was going to pull the engine and do the above next. While you're prepping the engine bay for paint that's when you work on the rust spots. Rip out interior. Paint trunk and floor board. Get that done install new carpet and get seat covers from Lengedary. I'm not a seat repair guy so I would have to send that out to a professional. Replace wheels with Weld racing after big bolt conversion.