I looked but could not find the readings I took years ago when I replaced my gauge with a VDO. I added a resistor to attempt to compensate between the gauge and sender. The result was a reading of full which is accurate but falls off as the fuel drops. I gave up and just measure it by hand occasionally not that I let the tank drop that much. I like to keep fresh gas at all times.
If I remember, empty was the zero ohms reading or close to it.