I picked up a 310 helmet from SLR. A 320 item seems unlikely. Even the 320 items from challenge mode raid are not guaranteed to help. 3 challenge mode Warpriests and all I have to show for it is 3 heavy at 320 when I already had a 320 heavy. The next time it rolls around, I could get 3 more 320 heavy. RNG means max level will never happen for some players.