I don't understand what you are gaining? You will still have the same shackle angle, but it will just look differant. The only thing you gain is clearance, like on the front when you have a body mount that limits travel. I don't think the lines you have drawn to give your shackle angle are correct either. I am no engineer so I could be wrong. You will only fool yourself into thinking your shackle angle is differant. I have added the lines that are correct. Your red line will not happen with no weight on the spring. The bend is irrelevent, the angle will only travel in a straight line. Look at my boomerang shackles with no weight and notice how they act. That should clear things up.
