It usually costs the same to process a one ton sample of 1 g/t as it does to process a 10 g/t sample from the same area. In the A-4 vein, the oxidized stuff near the surface would be cheaper to separate the gold out, as to what it would be 200m down. So you usually take an average cost for processing to allow for these variables.
I am guessing somewhere around $350 an ounce to fully extract the gold from most of the property would be a reasonable average. It may only be $150 average per ton, but I will use the $350, hopefully to be conservative. But, in this respect, you would be right, the more ounces in a ton averaged out, brings down your total cost.