Hey, just to let you know, Gyro Ball works better against faster pokemon, not slower ones. Therefore, EQ is the better choice to hit rocks with, and it gives you some coverage against fires too.
I know how much you like the idea of Extrasensory and so I reckon you should have the following move set with life orb as the hold item:
~ Earthquake
~ Thunder Punch
~ Fire Blast
~ Extrasensory
You may be wondering why I recommend Fire Blast over Flamethrower... With the life orb and lots of Sp.Atk EVs, the 'reliability vs power' battle normally ends up with power winning. This is because the the extra power Fire Blast has to offer becomes much more noticeable. I know Fire Blast has less PP, but its not as if mixed-sweeper, Typhlosion with life orb is going to last too long in battle!