Thanks guys, I hope to be able to actually do this one in a reasonable time frame.
John, here is a close up of the head, I think the facial planes are somewhere near right as is the size, any errors I can correct when I build up the features.
The size of the head is 13.75mm high from chin to top which = 220mm, 8.75mm wide across the cheek bones which = 140mm and 12mm deep from brow to back which = 200mm.