Mr B.
1.  GSV is in Nevada which is one of the lowest cost places to mine gold in the world
2.  While the strip ratio is greater most of the GSV resource is Oxide ores which is what you want in a low grade operation.  Sulphides are much more expensive to process. 
3.  The grade is not .7 but rather .77 I know it might sound like a small differnce but you are talking 10% and about 16% higher then Sirios which needless to say is quite sizeable in similar operations.
4.  This one is important Cap Ex for the mine is only 190 million compared to around 400 million for Sirios.  That works at to be about $118 an ounce vs $250 an ounce.  
5.  AISC does not include the cost of financing it typically assumes 100% share financing so now you have to add the interest should it be debt financing.  It is usually a combination of both but to arrive at a true cost you need to assume 100% debt.  It is often based on a libor plus scenario but for simplicity I will assume 8%!  So add another $120 an ounce to the AISC which brings you to $1141.  Now add debt payback which brings you to $1259.  Assuming same amount of reserves this number would be about for Sirios quite different.  Remember just running random numbers under similar scenario's.  So assuming Sirios base case AISC of $1021 plus $250 and ounce for Capex $1271 plus debt servicing about $1621.  So now that is quite a bit higher so that 16% grade differential is massive.  
6.  GSV has reserves Sirios has none so they are sme 2-3 years away with the need to do lots of spending to get there.