Perhaps you should go to the archaeologists for this.. Julian Richards was part of the Stonehenge Environs Project of the 1980s. probably done for Wessex Archaeology. I remember reading in his Photographs of Stonehenge, his crossness at the lack of proper recording and publication of the earlier excavations of Piggott/Atkinson..
http://www.archaemedia.net/st1.asp should be the link to Julian Richards site with map of the surrounding area of Stonehenge. Hope that helps, they probably did some computer reconstructions....