For what it's worth..
-Have your kiters install rangedisplay. They'll never die from crush again and they'll always know if they need to kite faster or slower (slower by laying 2rows of puddles instead of 1).
1 Tank, 6 DPS, 3 Heal.
-Tank and a Healer (Holy Pally/Resto Shaman preferred due to being able to wear a shield) take the frontal cone
-Anyone can kite, doesn't really matter, just swap the debuff at 10secs before a Crush
-The healer who is soaking the cone just looks after themselves and the tank, can also drop a few heals elsewhere if desired
-Assign another healer to look after the kiter, again can drop heals elsewhere if they like
-Final healer stays in the middle and looks after the ranged, can drop heals on kiter/tanks if they come in range
-Have a cooldown up for each Crush
You should 2 heal. Spirit shell the crushes. Disc priest are amazing. If all DPS excluding tank and healers are at 75-80k deeps your fine. There's not much damage going out really. The disc can pretty much DPS. But I recommend 2 heals! Gl!
We've got 4 dps pushing 100k+, you've got all DPS minus one at 70k or less. I think that could be a major problem for you.
If you can get 2 plate non-tanks to soak swipe, it helps a ton. Tank dps is so low without meaningful vengeance. My group kills him with 3 heals and 7 dps with our fury warrior in defensive and frost dk in blood pres soaking. You might be able to soak with your arms warrior and holy pally.