Bevildevil, I agree the index knuckle on bevil 1 and heelpad on bevil 8. That's exactly how I do it too. And on your article about Wawrinka, I don't see his heelpad near bevil 7. It seems on your photo it's on bevil 8, just like a normal E bh grip.
But I think it's somewhat important to note the index finger is not touching the middle finger for most pros. your 'mountain bike' phrase sounds like the index is touching the middle finger, which I wouldn't recommend.