Temperature should sit at your thermostat reading unless running under a heavy load. If you have a head exchanger and closed cooling with glycol you'll have a 180° or higher thermostat. If you use Lake water for cooling the engine directly you will have a 160° thermostat.
The engine runs less effeciently when cold so you get more plug fouling and gas mileage is down. You might be able to get more raw power out of it though for a short sprint because the cylinders could fill with a colder mixture. It's better to find the right one but nothing is going to blow up.