So I recently just had my 73 split bumper in the shop and had a complete engine rebuild (SBC 400 2 bolt main 509 block .40 over.) and its currently making 475hp and 495Tq. I have a 3 core aluminum radiator and I was told to buy a 180 thermostat but ended up buy one rated 160 degrees instead. I had the engine professionally rebuilt and was told that the 160 would be fine but I've been reading some forms where people are saying it's not very good to have a 160 due to running too cold. So my question is, is this a good idea or would it be wiser to go with the 180 instead?