So far I'm making good progress with the head rig having so far managed to block some weights for the head pivot bones and upper and lower jaw. It is still a little rough and with no real controls setup yet but it gives me an idea as to how the mesh will deform and what areas are going to be problems ones. I have also begun to block in the eyebrow deformers with cluster controls and, like the rest of the rig, they are a bit rough still but again provide a nice starting point that I can continue from here.