Whaler,
If you truly believe .20s grade makes financial sense, by all means go out and mortgage the house. If I were you though, I would wait a little longer till ISM releases the Recovery % rates on the low grade average, the bulk of ISMs Resource in the Micon Report.
2204 times .25 = 5.51 pounds per ton
Recovery might be 50% but you can put in higher numbers if you want.
5.51 times 50% = 2.75 pounds per ton
Multiply that by accountability to Xstrata @80 and now you have 2.2 pounds per ton
Multiply that by a realistic longer term Ni Price I would use 8-9 dollar, but in this example we can use the 13.00 price you like.
13.00 times 2.2 pounds = 28.60 a ton
Now take off your costs I will let you fill in these numbers for the board to consider.
Mining, develop, strip =
Overhead =
Transport =
Milling =
I think you find out grade and recovery means everything, and that is why the market is valuing ISM as it is.
Best
Nickel