Need help finding new temperature gauge

Well, 80'''ish ohms is not correct. The less resistance (lower the ohmic number) the higher the gauge reads. It should read 73--75 at empty, 23--25 for 1/2 and about 13 for full tank

The sending unit wire only goes one place.............connector at the sender.............up front in the rear harness to the kick panel..........from the kick panel to the dash connector

So if you have no continuity, check each point, IE from the sender to the kick panel connector. Make sure you have the correct wire. It is VERY possible that the sender connector itself is bad, corroded internally

You have the cluster out? Can you post a big clear photo of the back of the cluster?