5 ohm resistor on temp sender wire?

Thanks everyone for the great insights. Funny about the factory service hack to mollify the customer. Anyway, my plan is:
1) replace the sketchy ancient wire without the resistor to get the gauge working.
2) start and run the car, radiator cap off, until the thermostat opens
3) check the temp of coolant and see what 'normal' operating temp looks like on the gauge
4) Decide at that point to swap sensor out, add back in the resistor or do nothing. I am the only one that drives and maintains the car, so even if the gauge shows hot or cool from reality, I'll know where safe is.
Cheers,
Driver Ed