For cpu intensive games, you want the 8600K and overclock it.
You will get some 30% more cpu performance.
You need a Z370 based motherboard.
A decent air cooler is all you need if you have a good case.
Most K processors will oc to perhaps 5.0.
I think GTX1070 is appropriate.
But, if you have the budget, buy the strongest graphics card your wallet and conscience will permit.
I might suggest a EVGA GTX1070 just in case you might soon want more.
EVGA has a free 90 day trade up option if you should decide you want a GTX1080/ti.