Very nice bike it is worth what some one is prepared to pay as everyone says but I'd take a stab and say $2500 would be a pretty fair price.
Buyers market at the moment I have an 85 cr250 so easy to get parts for I will do it up probably spend more than it is worth but it doesn't matter if you aren't selling a bike to spend more than it is worth.
Are the Excel Rims on it?