This type of discussion is not unique to the Shelby's, but I do agree on this thread from a documentation point of view.
I have an early FFR Cobra, and FFR used to provide limiting straps so the shocks would not be continuously over-extended to the point of failure, and come apart. Like Shelby, the replacement with better shocks made the straps not needed.
But, a big point made on the FFR forums and technical discussions, and should be taken into account here, is that if the straps are too short, and limit body roll, this will hinder controlled body motion and cause some very ugly handling. By creating a travel stop on a solid back axle, the result will be the car picking up the inside rear tire in a very hard corner. Not what you want.
I do have straps on my race car, but they are long enough not to interfere with body motion, but will not allow the shocks to fully extend. That is how the straps should be set up.