Thanks haventaclue.
Looking at the serial number range on maxrules I now see that they went up to serial #4845300, when I first looked at boats . net they have serial # up to 1869775. So I was thinking that they ran from #175XXXX in 1965 to #186XXXX in 1978
Maybe the PO was mistaken with a rebuild date? After looking a little closer again, there is some kind of sticker (painted over) that 197X can just barley be seen under the paint with the right light and angle.
Just trying to figure out how much $$$ and effort we should put into it, after it setting in a garage for 14 years.