In case anyone's interested and hasn't heard yet, Bryan over at TwoWheelObsession.com did the retrofit into his '14 and it went exactly as I hoped it would when I saw the parts diagrams. Check it out!
https://twowheelobsession.com/2016/04/28/upgrade-2015-prior-fjr1300-2016-slipper/
https://twowheelobsession.com/2016/04/28/upgrade-2015-prior-fjr1300-2016-slipper/