Define "very high temp"- - - - - -is the coolant boiling? Original equipment temp gauges can be notoriously inaccurate, often indicating in the "hot" zone when the coolant is only moderately warm. The new radiator will allow you to use a pressure cap that will allow the coolant to get above 212 degrees without boiling, but only if you also upgrade the heater core to handle the increased pressure. Most original equipment heaters in good shape will handle a 7 pound pressure cap without any damage, and that will allow the coolant to reach 233 degrees without boiling over.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!