I'm only planning on replacing the motherboard, CPU and RAM right now. I'm heavily leaning towards buying the 6600k and motherboard you suggested. Maybe a different motherboard though as the metal heat sink at the top is going to interfere with my top radiator.
Just put my PC back together and here is are my fans just making it in with the motherboard with the plastic tip cut off the power supply cord. (ignore screws i rushed it)