Cooling Fan Sensor Help

[LDO]

I have an early model 283 that does not appear to have any sensor ports in the heads. I only have one on my intake manifold which goes to the temp sensor. The 2nd sensor that turns on my cooling fan is currently mounted into the normally plugged top hole on the water pump. This port doesn't seem to have the flow needed across the sensor to turn on my fan. Yesterday, my temp sensor read 207 and my fan never came on.
- I know the temp switch closes at the 180 mark as I tested it this weekend.
- I know the fan works because I have a manual override wired in and it comes on when I hit the switch.

I am considering this part as an option. "This 1" aluminum spacer mounts below the thermostat housing & gives you an additional pair of 3/8" N.P.T. female ports. These can be used for quick and easy connections for a temperature gauge, fan switch, or various sending units."

Looking to hear from anyone who has used it or anyone that can give additional advice or recommendations.

Thanks!
LDO