Temp gauge issues

74 model has a white plastic engine harness connector on right side of engine bay. It has temp sender wire, alternator wires, etc.., in it. These connectors do melt down to cause short circuits but... "sender disconnected, gauge needle goes home" does suggest a bad sender. No fault in that harness connector. Look at it anyway.
These senders typically fail to open instead of closed though. Ohms meter on the sender will prove it good or bad. With the radiator cap removed we can see when the thermostat opens. At that time the temp sender should show somewhere around 35 ohms.
Here's the thing... your temp gauge is the old standard 20 ohm gauge. Your fuel gauge is the only other gauge on this circuit and its a later design 13 ohm gauge. You can check that with a ohms meter post to post on the gauges as well. Neither gauge should show continuity from a post to can/chassis ground. If the temp gauge does... its bad.
For this model/design, a faulty instrument voltage regulator will show itself in the temp gauge ( wild needle swings ). The fuel gauge may be a bit erratic, show more gas than you actually have. The 13 ohm fuel gauge isn't as accurate as the earlier 20 ohm gauge but... it runs cooler, lives longer.
Bottom line... proving sender, gauge, wiring between are good, suggests the limiter is the culprit.