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The FSM engine manual that covers that series of engines (incl. 117.968) describes the operation of a nominal 80C thermostat as follows:
Up to coolant temp of 80C - stat main circuit closed, bypass open
Above 80C, below 94C - main circuit opening, bypass closing
At or above 94C - main circuit fully open, bypass closed

The correct operating temperature? Depending on load, and ambient air temp, an engine that is "up to temperature", may, in fact not reach 80C (Jan. in International Falls), or may go over 100C (Aug. in Death Valley).
With the exception of such extremes, anywhere between 80C and 94C should be considered as "normal"; good judgement counts.