Is the coolant boiling? Does the temp go down when the vehicle gets up to speed? If you can answer "No" and "Yes", respectively, don't sweat it. A 15 pound pressure cap will let the coolant go to 257 degrees before it boils. Just be sure to run a recovery tank so any coolant that pukes out will get drawn back into the radiator as the engine cools down.
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!