new waterpump which is best to use?

Many guys use the Weiand cast aluminum pump. This pump not only works well, it also has no water bypass passage cast in, so you are free to use any Ford thermostat you wish, since the stock warm-up bypass feature is not operable. This alone may reduce your water temp by 10-15 degrees. I've had one for 10 yrs, and I currently use a 180 degree thermostat for a 289 Mustang. I believe Chev thermostats also fit in an emergency. Warm-up in cold weather takes a few minutes longer, though.