1969 RS triple black 4 speed

[70Z28RS5151]

What is a fair price to pay for this project?
Non original drivetrain. It's a roller.
It is a Van Nuys car with original trim tag intact: 713 interior, 10 B paint and top, original rear fold down seat, seats need recovering, GM cowl hood. Car comes with all trim and gauges. All the RS stuff is there... I think.

It needs a quarter panel and trunk pan because of rust. All other areas are solid and straight. Owner claims it is an original SS car, but I don't know how to tell without the original drivetrain.

Thanks, Tony