Well, here in Arizona, none of this would be a problem. I can buy a “fixer-upper” car, store it on my property for as long as required until I get it running properly, then take it through emissions and then proceed to title and register it in my name. I would not owe a dime in fees or penalties, regardless of how long the car sits with an expired registration. I don’t have to insure a non-registered car, either.
However, in California, you would be expected to pay all of the registration fees and penalties to bring it current. Hence why many California sellers advertise their older used cars on Craigslist here in Arizona!