So after sketching the six heads, last weekend I decided to pick one and model it. I made an organized base mesh, sculpted it in Zbrush, then went back to Maya with displacements/normals and rendered my look-dev passes, (diffuse, SSS, primary spec, secondary spec, skin reflection, eye reflection, three different cavity maps and the blurred HDR background) which are here comped in Photoshop. I haven't begun any texture looks yet, so this is just the comp ready to go. All of the passes are at 100% but it looks kinda cool... although in the end I imagine it will be quite different. Now I just need to find the time to keep working on it!