1 oz per ton Would be a bit better than Fosterville current production and about the best gold grade mine in the world. Not as good as SWan Zone but Fosterville is pulling from a few different zones in the mine in order to deliver the results we see currently.
I use 10g/tonne as is both looks reasonable close to the average at Golden Joint and in general is a decent profitable grade above the average of an undeground mine in the world today.