That cooling system was probably designed to run a 7 Lb. pressure cap, which would let it boil at 233 degrees F. with plain water. A 50/50 antifreeze mix would probably take it to 240 or so as long as you have a good pressure cap and no leaks in the system. I think you're going to be OK unless it starts going to 200+ regularly.
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!
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