>I mean- I know the calculated figure for fixing Silbury and I would rather have that done than dig up stones that we don't know which way up they were let alone which way they were pointing and in what period.<

Well if it came to a choice between fixing Silbury and standing more Avebury stones up then I'm with you that Silbury has priority. But I doubt if it ever would come to such a choice and, you know, it's also about what we <i>think</i> should be done - because if we don't think about these things we don't really care one way or the other.

As for not knowing, "...which way up they were let alone which way they were pointing..." I suspect modern tests on these stones would probably give us a fair indication of their original alignment if not their exact original position - might be completely wrong about that though :-)