Ninja,
With the 50/50 i would just alternate the LED's that will give you an even mix, and make sure you put each color on a driver(well 12 - mayb 14 15 depending on the LED u got). Did you end up with XPG/XPE LED's or the XRE for blue and XPG for white or XRE(white/blue) this will come into play with how much you will be dimming your whites to get that color you want.
12 LEDs Per Strip
B W B W B W B W B W B W
W B W B W B W B W B W B
OR
8LED's per Strip
B W B W B W B W
W B W B W B W B
B W B W B W B W
I run 4 of the 23X4." heatsinks with 12 LED's on each so mine are really spaced out, but you shoudl still be able to fit your LED's in that heatsink. You are going to have a heck of punch in light! make sure you use a fan, or it might get a bit hot. I ran mine without fans and it got hot but not too bad, so i didnt have them on after a while. The absolute max temp on these things is about 150c, which is a lot of heat but just try to keep it cool enough to be able to put your finger on the heatsink without burning yourself.
GL!