Is this '72 Duster 340 worth the price

Based on what I see and what things cost I think it's in the ballpark. If I were doing it I'd try for 13k but depending on how bad you want a car 800 is nothing.I saw that the air cleaner was wrong for the car? Heck, sell it and get the cheaper correct one :}
It's very presentable the way it is. Go for it.