Someone has eliminated the whole choke system, including the thermal coil that's supposed to bolt to the flat spot on the intake just below the carburetor. You would need to replace several parts, including the linkage between the choke pull-off and the fast idle cam to make the automatic choke work properly, before reconnecting the vacuum line. People who don't understand (and don't want to) how an auto choke works take the Mr. Bad Wrench approach and just disable everything.

The temp sensor above the thermostat was used to control a vacuum-operated heat riser valve and other accessories on emission-control engines from the mid-1970's and later. Unless you're trying to conform to some sort of original wiring diagram for a smog inspection, just ignore that sensor. The normal temp gauge sensor should be installed on the driver's side cylinder head between the #1 and #3 spark plugs.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!