I went with super miata coolant reroute kit, and after installing the head plug I realized that there is no room for a fan switch.
I cant find a inline temp sensor housing that fits 1/2" NPT sensor

Is there a 32mm inline housing that has a 1/2" NPT thread? I can only find 1/8 or 1/4.
Is there a 1/8 fan sensor switch that I can use?

I dont have a standalone, and I dont want my fans to be always on. Looking for a way to run the OEM fan switch with the head block off plate.

 

I'm assuming a couple things here, some more info would have been helpful.

You're using the coolant reroute on a 1.6L motor, which has the fan switch on the water neck in the stock configuration?

You're using the head block-off plate from the SuperMiata kit and not using the stock water neck?

After a quick look, the head block-off plate does not have any holes in it for the sensor, and this is your issue as I understand it.

Best option is to put the water neck back on and use the plate with the holes in it.

More complicated option is to extend the wiring for the fan switch, use one of the 1/8 npt ports on the reroute thermostat housing, and a generic 1/8 npt thermo fan switch.

From a few seconds of googling, it looks like the turn-on temperature for the 1.6L is 207F.

"1/8 npt thermo fan switch" is a good search.

 

The other option is to remove the block off plate, drill and tap a thread in it and reinstall. Personally I'd extend the wire to the back of the head and use a generic 1/8th thermo fan switch at the required temp. Clean and neat.

 

I bought an inline adapter for 1/8th and will tap it for 1/2ntp