overall stock height for a fastback

Well, with that many changes to the suspension, I don't think the stock height is relevant. There is certainly no way to measure the "ride height" using the factory procedure. And until you get all the weight back into the car (glass, interior, hood, drivetrain?), you don't know what the height is, anyway -- it will lower itself with every part you add. I would say, wait until it's all together and just set it up so it looks good to you. BTW, the 1967 Barracuda brochure lists the roof height of a V8 fastback at 53.4 inches. Remember, your tires will be a big factor, as well.