Hello.

I'm afraid that you are about to discover that some things are rare for a reason. One thing that would be hurting that car would be that, after it's all said and done, it's a 68 coupe, which occupies the lowest spot on the vintage mustang body style totem pole as far as value goes. For most people a 2bbl big block makes no sense, since a 4bbl small block car will outrun it. The first thing that a lot of people would do is yank that 90 lb 2bbl intake off of there and put either a 4bbl, 3 deuce or dual quad aluminium intake on it to lose 50 lbs and probably gain 50 hp. Personally, I think that the bench seat is pretty cool, but few share my enthusiasm for them. Having A/C is a good thing. In really nice condition, that car would bring something like 20k assuming that it isn't a color like lime gold or diamond blue. If the paint is pretty tired and it needs pretty much a new interior, but runs and drives ok with no brake, suspension or steering issues, you're probably looking at something in the 10 to 12k range. A lot of people would look at it like it isn't an outright project car but it doesn't miss that by much. Hope that helps.
