165 degrees says your injected. Is that correct?
Carbed engines run a 140 degree thermostat. The temp will still be around 160 degrees.
Do you think you have a problem? Why are you asking?
My '96 1/2 raw water cooled 5.7L (carb) reads 175 on the gauge. It has the 160 degree thermostat. If you are raw water cooled, previous owner migh have had a 140 installed. I belive the lower temp is prefered for saltwater boating.