AS a rad that size is bound to require a exterior mounting set up, why not 2-192 which is larger yet. And due to it's more square shape should have lower resistence due to the larger number of tubes per pass & slightly shorter passes.
The heat from 3 TEC's + 3 O/Ced chips + pump heat = A heck of a lot of watts! !
So the more cooling the better.
What pump, fans & blocks do you intend to use for this set up?
Edit:
2-192 10.75 X 10.25 X 2 = 220.375 cubic inches of volume.
A solid 10% increase in rad size, yet should offer lower head loss.
Should make for a extremely powerfull system! Congrats !