The September quarterly report has some info on width - 3.7 metres, but does not mention SG. Like you I am no geo. However I assumed, or was told, it had an estimated SG of 2 or was told that, although I am aware of other deposits with higher value (PIR at 2.1, from memory).
The September 2011 quarterly report has a lot of interesting data on Nabanga - did you read it?