Its kind of a tough question. The things that will affect the price are if they have been ported(plus), are you absolutely sure the valves will keep and be ground again, do you have to have new guides installed? If the screw in studs are really old they may need to be replaced as well. What I try to do on stuff like this is find out what the cores are worth at the machine shop and figure up from there for the extras. There is some desireability factor because they are the early heads.
You can see my 65 fastback at: http://hottarod.stangnet.com/
You can see my 65 fastback at: http://hottarod.stangnet.com/
