Man you weren't kidding when you named his pistol!!
I would definately lunge him with his tack on. A round pen might be better if he decides to go nuts on you. Let him walk around next to you with the tack on - let him get comfortable. If you can, have someone ride next to you. Another horse might help him realize he isn't going to die . I doubt eating will help at all. Every few steps he takes while you are on his back tell him what a good boy he is!!
I don't have an incredible amount of experience with fast horses (mine is slow as hell). Just remember to be patient . The only reason he takes off is because he doesn't understand!! Good luck!!