LED count Pentagon Corner tank?

The dumbest thing i ever did was buy my tank. But now i want to upgrade its lights and am all but ready to do everything else involved in that except getting a real fix on the LED count i need.

The tank is a 24x24x30" deep pentagon tank, so its footprint is 24x6" + 18x6" + (18*18")/2 or roughly 414 square inches.

Now i figure i should get 2 squareish heat sinks and mount them so i can angle them in, so basically cross beams of the 2 lights to get a little under the rock shelves i have (instead of just blasting the top floor of the rockwork). This would also allow me to place them farther apart with wider lenses and still not waste too much light spilling over the edges.

But, how many LEDs should i put on each unit? With my drivers the LEDs will need to be in strings of 6 (CAT4101) so multiples of 6 is really the goal. I also am not convinced that Cree LEDs are holy and will gladly look at Bridgelux ones as well.

So how many Cree XP-G/XP-Es should i have on the 2? How many Bridgelux LEDs should i have? (And for both, what ratio would get me 12k-15k in color without excessive dimming of one color?)