I am currently putting a new head on mine. Didnt need it but wanted to be certain since I'm rebuilding it anyways and I wanted to switch to the newer flow design. I will be moving my thermostat to the upper radiator hose. The 1KZ has a built in oil cooler though. Did you feel that it wasn't doing enough? I also switched to a full size 3row all aluminum radiator, which made a huge difference.
