Thermostat choice for my Duster 340

The 195* t'stats showed up on the '72-'74 timeframe, with the first generation of emissions devices. It helped reduce hydrocarbon emissions.

Hotter temps tend to reduce engine wear to some degree, but the difference between 180 and 195 may not be that much. Running a cooler t'stat gives you a bit more cooling margin for transient hot conditions. I'd go with the 180 personally, mainly on long ago experience with the 195 engines running on the hot side 'back in the day'.