We killed this for the first time just last week and I am also in the same position as yourself, normally elemental but went resto as we 3 healed alongside a disc and resto druid.
For our kill night I made a decision to switch to guidance over rushing as I went with the logic that most of the healing is required on the stack phase rather than the kite phases (I was often dpsing during those), and I have to say the results were simply awsome. If done to the normal stacks (20+,5+,20+ etc) you will have AG for every stack phase (if you use it before Asend and Tide) and it was even more beneficial to me as I switched from using chain heal to blanketing the raid with riptides while maintaining healing rain, this btw was awsome for guidance.
http://www.worldoflogs.com/reports/q...?s=6775&e=7311
The above was our kill and while I dont resto too often I felt I did pretty alrite.