3/8s NPT thermostat connection points - fan relay & water temp gauge

At this point of my motor installation, I am working on water temperature gauge (part of a external gauge cluster) and electric fan relay

1991 LA360 Stroked to 408
Eddy 7576 RPM Air Gap - existing 3/8s using for heater hose
Eddy Heads - 60775s

The electric fan relay - thermoswitch is 3/8 npt ( I can use 1/8 npt) - if I want to connect to the intake manifold
Water Temp gauge - capillary is also 3/8 npt with a fixed fitting

I am sure this is common - where and how is everybody connecting these switches/relays?

I did find a water neck spacer that has two 3/8s ports. Anyone using one of these?

thanks for the help/education

bolts and fittings - eddy 7576.jpg

mez-wn0028s_w.jpg