Toss up between a 67 and a 69 for my favorite year Mustang fastback.
That is one rust-sick puppy (and not in the cool kind of sick either). No doubt you'll do a first-rate job, but it will be interesting what else you find as you "peel the onion." Regardless, I look forward to progress pictures!
Bob Enjoy life now -- it has an expiration date. ~Molɔ̀ːn Labé Skýla~