A friend of mine has a 76 D200 318/4speed (granny low)

Hes running what he thinks is the factory 190 or 192 thermostat.

On his aftermarket mechanical gauge, while towing on a hot and humid day, the truck was running around the 200-205 mark.

I told him that if memory serves correct that anything under 210 was still safe, and that at the 220 mark you needed to start watching close, anything much above 220 was time to shut down, slow down, or take other actions to cool down.

Did I give him correct advice?