Check the FSM for adjustment procedures and such. At 70 degrees F, ambient (everything, meaning engine too), the choke blade should just close by itself. Not a hard close, but a "give it a nudge, possibly" type of close, to me. Colder than 70, then the closing force will be stronger. When the engine starts, the choke pull-off diaphram (on the rh side of the carb, near where the choke attaches) will open the choke a specified amount so that the engine will run and not choke down. Is that diaphram on your carb hooked to a vac port and operational? In order to check the "choke pull-off" adjustment, you can manually compress the shaft going to the choke blade with the engine off. To check the diaphram, you with the shaft manually compressed, you can place a fingertip over the vac hose nipple on the choke pull-off unit to see if the diaphram stays compressed, if it does not hold, then a new one would be needed.
As the engine warms, the thermostat will ease its tension and let the choke blade open fully. As you might notice, the blade is not centered on the shaft, so that air flow through the carb will open it with higher rpms, if needed.
None of this really has any direct correlation to the engine coolant temp, although they are both related. KEY thing is that the heat crossover on the intake manifold is OPEN and working, which is where the choke thermostat gets its heat from.
www.mymopar.com for free download of the Chrysler factory service manual, if needed.
Hoping this might help explain what should be happening,
CBODY67
----- Edit, a few hours later -----
That thermostat looks more like a Carter 4bbl item than a Holley 4bbl item, or am I looking at it wrong? Picture of your Holley on the car with that thermostat and the prior carb?