Its all in what you want. The truck has very little collector value and the newer (1987+) can haul more, haul it better and with better mileage. While it only shows 47K miles you have to remember in 1973 a car was worn out at 100K - that's if the mileage is correct.
I personally wouldn't consider giving anywhere near the asking price. From the pictures you can tell the paint is in pretty rough condition and the rest of the pickup is by no means "slick". If it where a garage kept pickup with no rust the price wouldn't be all that bad.