I personally don't use the blue light spectrum(6500k) at all anymore. I am strictly on the 2700k lights, so no you don't need the 6500k lights, but they do aid in vegetative growth. As for flowering with only those lights, yes it's possible, but you want the plant to get as much light to it as possible. I doodled up a little sketch in MSpaint to help get my point across.

Using multiple 2bulb splitters will work better than just the 68w, you want to surround the plant with lights if you are using cfls for flowering, because they have barely any penetration power, so if you have any type of canopy you are going to want side lighting.