I keep a 767 in turbulence at about .78, as per regulations. I have found that most British 767 operators (AIH, BAL, BAW, etc)will keep a normal cruise speed of .80, no more. In light turbulence it is kept at .79 but it doesn't make too much difference higher up. It's low altitudes like 290 - 330 that will worry me.
A VREF can go as high as about 179 with 190,000 kgs aboard, it all depends, but like the other one said, it's from 119 up and can really be varied.