Interesting.
I evaluated it using it's enlarged form (because any decent DM will ensure it's enlarged if it's a feature fight).
Shouldn't Hitpoints be 114? 12d10 + (Con Mod x 12) = (5.5 x 12) + (4 x 12) = 66 + 48 = 114
I think that, along with Cone Of Cold, will bump the enlarged form to CR9.