["QUICK-SILVER"]

First things first: DON'T take ohm readings with the ignition switch on.

Meter should've been set on DC Volts with key on.
We all ready know, from previously grounding the sending unit wire, that voltage isn't making it through the temp bulb out to the sending unit wire.

Key off, if everything was working "RIGHT" on your car, you should have got some kind of ohm reading checking sending unit wire to ground. With the single power supply to the printed circuit, at minimum you would have seen temp bulb resistance (in ohm's) and fuel guage resistance from hot to ground, plus any resistance in the wire length envolved.
Most fuel gauges, in those years, will give around a 150 ohm resistance reading from hot to ground. Add bulb, wiring and resistance through engine/body, you could end up with something in the 150~200 ohm range. That's testing sending unit wire to ground resistance in ohms.

This is important: you need to play with the new meter and learn the difference between 0 (zero) ohms and infinite. Both can show zero's on the meter. 0 (zero) ohms is no resistance at all. That's the reading you should get when touching the two probe ends together...... Probe ends not touching anything is an infinite or open reading. Typically it's a figure eight laying on its side in front of the zeros. Like this: ∞00.00π.

Not knowing how to use a meter correctly will hurt more than help.
So play with your meter and get a feel for it. Check a straight piece of wire, resistance through a bulb, plug wires are really interesting, across a coil, just whatever it takes to get to know it.
Applying that new found knowledge to diagnosing electrical problems with cars ....That'll be another learning experience.

Have fun with it and let us know what you find..or don't find.
Clay