need some help with car value

value of the car is what you are willing to pay. I live in the rust belt and I will pay extra for rust free as you would get buried financially doing panel replacement and never get all the rust. If you want to make it perfect, paint it and a new interior and then update all the drivetrain, I would buy one that is like what you are going to build and let that builder take the hit. On that particular car if you just clean it up and upgrade the drivetrain I think that is a fair-good deal. Just my opinion and I have many ask my wife.