Forgot to mention that before the new impeller or complete water pump kit is installed remove both lower leg's water intake screens and clean each sides of them, clean the screen's cavity and poke up down a small diam wooden sushi stick through the upper water orifice until it comes unrestricted seen out the screen's cavity.
Everybody overlooks this hidden water passage, just change impeller or water pump kit, thermo and voila. Could be already with reduced diameter due to crap, filth, marine growth, etc already built there, If impeccable cleaned the impeller will suck and pump more water towards the crankcase. If the motor has not built already too much salt crusts, scale, crap whatever in the entire crankcase's water passages said motor will cool much better and pee strong as a reloaded teenager guaranteed.
Happy Boating