I've not driven a DMC-12, but lack of power steering doesn't seem like that big of a deal to me? All the vehicles I've driven without power steering have been ok; usually the steering wheel is much larger to give you the leverage you need; it's not as bad as you'd think if you've used a car with inoperative power steering.

But yeah, I had a nice conversation with a guy who kitted his out as a movie replica at a outdoor showing of the film. He said it was fun to go to events, but it's terrible as a car. And some of the parts are unobtanium, like the flux capacitor. Not that that's unique for cars in that era, try finding a federal EGR filter for an early Vanagon; just gotta hack around it.