The sunroof looks like it cracked open, that can't be a good sign.

 

I'd hate to see what the unibody looks like after just sitting there that long. Sight unseen I wouldn't pay more than 3k for that car.

Once I got under it the price may go up a little. I can almost garunteed there is through rust in multiple places throughout the unibody. Then there's the fact that the car doesn't run obviously. Worst case full drivetrain there. You're already way past what you can buy a running one for.

Oh lastly you'd be hard at work/or dipping deep into the piggy bank trying to get that SS RR paint to even look somewhat presentable. Further upping the price.

Only way to know is to go over it throughly with someone who knows what to look for as these cars age.