Run the normal nonpressurized radiator, then chuck a hose on the overflow tube and run it to the overflow tank. then make sure your rad cap is sealed tight, and have an unsealed cap on the overflow tank. Best of both worlds. You don't need to raise your boiling point, if your radiator is good it will run cool. If your radiator is partially plugged all you'll end up doing is ruining your engine. Speedway makes a nice one:
https://www.speedwaymotors.com/Speed...Tank,2954.html