Robert,
That chart is a keeper. Looking at my notes on page 90.20 in the Bentley, inputting 35 ohms (on my truck) gives a full reading. 210 ohms equals empty. On the next page, 340 ohms resulted in needle position I (cold) and 30 ohms sent the indicator to position II (hot).

With this information, you could go to Radio Shack and purchase some resistors to test the calibration of your gauge. Just unplug your temp sender and substitute a known value. 
Good Luck,
Ken Lewis
http://neksiwel.20m.com/