Kha'zix is like talon, you go in and then go out fast, that's why you should evolve your E at lv 6 or 11, not at 16, otherwise your way of doing dmg will be seriously low.
Having E evolved is important, as long as you can get a kill or an assist you did your job, and it means you can do more dmg afterwards. The only tank item he needs is GA, rest just go LW, BT and ghostblade and another BT.
Gz on gold by the way Rozzis.