Keiller found the original socket holes dug into the chalk. They give a good indication of which way up the stones was originally and what direction it was orientated and what depth the stones originaly stood.
I doubt Avebury will ever get the restoration it deserves.
Mike Pitts' proposal to EH will effectively stop other archaeologist doing something similar for a long time. EH are keen to leave things for future archaeologists to find with any new techniques that may be created.
What worries me is that if they let Mike pick one stone up they may say 'No more' because there is nothing of value to be learned by picking up any other fallen stones.
On the other hand excavating a stone that was buried in the middle ages may reveal a lot more.
PeteG