The reason you would have wanted the 1060s would be for the power efficiency rather than the ability to over clock, This is the reason youve seen people lower the power limit to 65 since this will cause the card to draw less watts. My 1060 pulls 60w yet still hashes at a decent rate, Id advise going for efficiency.

You can use something like msi afterburner to over clock each card in the rig of 6. I dont think its possible to over clock them all with one profile over individually.

Best way to test mh is just run whatever coin you want to try.