Running, driving, big block vert that isn't a rot box/basket case is definitely worth 30k. They are rare, with high quality examples bringing a lot of cash. You should check the trunk, floor pan, cowl for rust as those tend to go first. Obviously you'll want to check out the frame rails as well, along with the rockers, wheel wells, etc.
Be aware that certain parts are vert specific and not remanufactured, like the rear interior panels.