There is a 1968GT/CS Big Block originally a S code and now with a 428ci engine, for sale on www.vintage-mustang.com. See 1967-68 cars for sale. Posted today. Good Luck!!

I see this guy is in Washington. If anyone is interested in the car and if he is in northeastern or central Washington, I will go look at it for you and give an "objective" appraisal, at my convenience of course. We're kind of snowed in up here at the moment.
Steve