360 Tune Up

I'd try living with it and doing some more monitoring.
As long as it doesn't creep up 210 is fine.
On the measurement side,
Might boil some water and hang the sensor in it to confirm 212 is close to 212.
Most thermometer devices are not particulaly accurate.
Might add an oil temperature gage. That's another really useful indicator of how the engine is managing heat.

Check system pressure is holding.

Is there any sceening of the radiator in front? I know its likely but figured I'd mention it. Screens start to look like walls the faster its moving.

Poking around Speedtalk, there's discussions of coolant temperatures up to 230-240*F can be fine, depending the pressure. That is there has to be enough system pressure to keep it from boiling at those temperatures.
Chevy at 220- 230 Coolant Temp - Page 2 - Speed Talk

Engine wear, test summary quoted from Stockel on page 2.
optimum coolant temp for longevity - Speed Talk

Distilled Water? - Page 2 - Speed Talk
Sequence of failure when coolant overheats? - Speed Talk

This guy was worried about 220, so some of it is personal tolerance, and again what the system can handle.
PONTIAC 350, circle track race engine, RUNNING HOT. - Speed Talk