There is absolutely no doubt about the size and grades of B4M. The Blue Bros early in the game tried to keep that under wraps.
It may be worth re reading some comments from Sam Walker, a team leader from PIRSA, that I posted on my old neglected blog a few years ago.And we know even more now!
http://www.deeplode.com/2009/09/south-australian-government-and-ags.html