A "good" temp range would be 200 to 225F.
Your oil should not go above about 260F for very long. Getting the oil to 300F (even for a short time) would probably be real bad.
You want the oil to go above 212F (at sea-level) so that you boil out any of the water that condenses in the oil as the engine cools down after running.
This is sort of a problem with some of our cars, because they may just be "lightly used" and driven rarely. In some cars the oil rarely goes over 150F. The only solution is to change the oil more frequently (and try to give the car a "good run" more often).
My Spridget (with the 1500 Spitfire-based engine) rarely got above 215F and it was only used for racing. The regular water cooling system kept the engine (and oil) pretty cool. This is why I never bothered with an oil cooler. I am changing over to a "new" (1275) engine and I'll be monitoring the oil temps. If they're under 220F, I'll won't add an oil cooler.