Is there a large pipe plug near the heater hoses? That's usually the place for a mechanical temp gauge. And you can put hose adapters on that and have it inline on the heater hose.
I believe this is a /6 so who knows.
There are multiple ways of dealing with that.
I have had to do both our Mopar small blocks for mechanical gauges, so the tap is in the toolbox.
Both aftermarket intakes.