You should be able to run a 6700k on a z270 without a bios update... the R6 will support and shipped with the 7700k. But if the R6 didn't originally ship with the k cpu, you will need to add the vrm heatsink which only shipped with unlocked cpus.  Also, you will need liquid cooling.
I'm trying to upgrade my Aurora R6 CPU from an i5-7400 to an i7-6700k. Does anyone know if the i7 is compatible with the R6's motherboard/BIOS? 
Aurora R6, i7-6700k CPU compatibility?