So I've been doing some work on my 53 merc. I've got new thermostats water pumps and I've had the radiator boiled out. I've got a infared thermometer and the heads around the spark plugs are reading around 190. The center at the 8cm is reading 200. Is this about right? The heat gauge is running above three quarters on the stock guage. I have 160 thermostat in it. Thanks!