cast iron water pump vs aluminum pump

I found some different pulleys to try crank is now 6 3/16" dia, fan is now 6 7/8" dia, they must be mix matched because I had to space out the fan pulley, and re position my alternator a little,anyway I had the car out for almost 2 hrs today in 86 degree weather and the temp gauge stayed at 180 rolling and 185 in traffic, the odd thing I still have the 160 thermostat in and even with the pusher fan running it won,t cool down below 180. I can live with this compared to 220-230 I was seeing. I think if I ever find the correct size pulleys or maybe change to the hi flow pump it may get a little better yet. But for now its running and my new tti headers/exhaust sound real sweeeet.I am a happy camper Bigmoe