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I doubt if this is causing the overheating, if you mean that water is boiling out of the radiator.

Two tests:
1. Test the radiator flow: take off the lower hose of the radiator. Block it with your hand, and fill the radiator with plain water. Take your hand off and the water should gush out in as big a stream as the lower opening. If it runs out in a smaller stream, the radiator has blockage inside.

2. Take the thermostat out and do the same with the engine ... it should run out fast. By the way, a 180 thermostat is good -it'lll often take away ping so you can run regular gas again and you can put a 7lb cap on instead of a 14lb (easier on the radiator).

If you mean that the gauge goes over to the H side (but doesn't boil over) -- that's probably just the dashboard gauge. Test it with a real calibrated test gauge. If it's going signifcantly higher than the thermostat rating ... most likely the thermostat is bad, radiator too small, electric fan not effictive. The stock radiator will heat up when it's 80 degrees outside, but not boil over. But it won't break the engine unless it boils the water out. Fitting a larger B210 radiator will make it run cooler.