Well, if its an 87 Turbo Limited- thats one of 1035 cars. Which makes it pretty rare.
But, the salvage title kindof cancels out any special value.
I think your dad is right about dead on. You can buy a nice roller, full interior and decent body, for about that kind of money. Since that car needs quite a bit of body, interior, and mechanical I would put it down in the low $2,000 range.
I'm not an expert by any means, and I'm pretty cheap, but I have been doing some shopping lately.
For comparison,
I have a strong running, perfect interior, rusty / needs paint (its shiny, but repairing the rust will make it require paint) - 87 GN that I'll be selling for around $5,500.