WIW..1989 Ramcharger
I personally love ramchargers. On my 4th one which is an 87. I wanted a 2wd version before I got my current one, bit it was boxed in by buildings and a mobile home. Seller wanted me to move the mobile home in order to get the RC. Walked from it.
All RC have rust. I had to replace the lower 1/4's and rockers, which wasn't that bad. I think it could be a great project for the boy and fairly easy to get parts for. Its worth what you are willing to pay. I would offer a little less, but if it's complete and in great shape, well that decision is yours on what to pay. It looks nice in the pictures to me. How's the interior?