[chevytruckluver]

I would run a 180 deg thermostat if it were me. If you think about this when the water is circulating through the engine it is stopped inlarge part by the t-stat until the t-stat reaches its setpoint in your case 160 then it opens and then water moves through the radiator. When the t-stat is closed and water is stopped in the engine it is also stopped in the radiator allowing the air moving through the radiator to cool the water back down. If you run a cooler t-stat the water wont stay in the radiator long enough to cool back down. just my .02
good luck with it