I think as Kadie mentions about hanging for a few days will assist roots to heal before replanting. The root pruning would be completely a personal thing. If planting into a very shallow pot it would be needed, but going into a pot 10" or deeper (not too deep), it would not be necessary.
When you say that the roots measure 9". Is this from the end of the feeder roots to Where? on the caudex. Much of the caudex on this tree could be exposed. The feeder roots should be somewhat spread out when repotting and not straight down.
A even pruning of the branches once you have repotted it, would give a nice new flush of blooms in the summer. Prune in a half semi circle shape like a mushroom top.
This will be a beautiful specimen. Very nice.
Rick
