tailpipes and a spring relocation kit?

Though it may be a little late, I think you could probably still run pipes to the back with a full inboard spring kit. You would have to snake the pipes between the frame rails and the leaf springs, but unless you completely bottom our your springs you wouldn't really have to worry about them getting hit if you keep them tight to the frame rails. At least from the looks of my 67 Dart you could. Can't say for sure though, hopefully someone else that's done the spring kit can chime in.