Not sure i understand your last paragraph. If i took the DFS at face value it was for the purpose of creating a valuation for our discussion. If the FS is exaggerated, then it only enhances my supposition that it's not viable.
Ok you want a level playing field, let's compare apples and apples. Wiluna OP indicated vs Gruyere OP indicated (Only reason i haven't used M&I is because BLK haven't proven Wiluna yet.) Using your formula:
Wiluna OP (1/(2.6*0.82)*13 = 6.01
Gruyere ( 1/(1.27*0.92)*2.8 = 2.39
Using your AISC chart
https://hotcopper.com.au/attachments/blk-jpg.1020931/
Wiluna OP approx 1650 AISC
Gruyere approx $1100 AISC
Yet they used the same cutoff?? If BLK have low balled for the purpose of getting ore into the mine plan then again this makes my point about the quality of the resource. It also has to make you seriously question the underground and other inputs.
Then you have the small issue of needing $115m or so to fund the expansion.
