I'm 5'8" and I ride 180s for park and all mountain, 190s for powder. I think you'll be fine. The 170s are just at the top of my forehead, you definitely want to go longer than that.
tails are rockered too, don't know if you meant that as well with the "tip rocker".
also the watch lifes are pretty soft, but i haven't skied on last years to compare. they're a great park ski either way, and definitely go with the 180.