Along this same line, is it possible to swap out just the cage from an SS to a GS on a Shimano road RD in order to accommodate a wider range cassette? Specifically, I have an Ultegra 50/34 crank, a Dura-Ace 7800 RD (short cage), and a 11/28 cassette but would like to go to a 11/32 if a cage swap is not too difficult. If that can't be done would my drive train allow for a 12/30 without any other changes?