1964 Ford Galaxie High Temp

I recently installed a 390 cu in motor in my car. This engine was rebuilt. When driving the temp runs around 200 deg. In slow traffic or going up hill it may go to 215 or a little higher. I nstalled a 195 thermostat. The radiator was cleaned and checked. A couple of people told me to install a lower thermostat? Will a exttra fan work? Any help will be most appreciated.