I have taken readings on the same car.
I get 40 ohms @ 100C
55 ohms @ 90

Also, you want a reading at the temp sending unit location/thermo-housing . The reading at the radiator has already dissipated heat.

As you may have noticed , the temp readings in relation to the resistor changes are non- linear, so a fixed resistor value to change the reading will only accomplish this at That specific reading.
In other words, the other readings will be off as the fixed
resistor/thermistor combo effect is different at different temps.

You also want to make sure that you are taking your resistance readings with the gauge wire disconnected from the sensor.
[to eliminate incorrect R readings]