Carb and Divorced Choke issue

As quickly as you can, get the three books described in this thread.

Tune-up parts and technique suggestions in this thread.

Your engine is about due for its first(!) valve adjustment.

Probably the original carb with such low mileage. 1974 was the first year for the Holley 1945 and they didn't quite have all the bugs worked out. Go through it with a good quality carburetor kit (I like the ones from www.daytonaparts.com ) and replace the foam float with a brass one, Walker #100-48.

Secondly: Find the rubber hose that goes to your ignition distributor. Reroute it (or replace it) so that it goes directly from the distributor to the spark advance port on the carburetor without stopping at the widget on the air cleaner body. This will greatly improve driveability, performance, and fuel economy, with no negative effects.

Firstly: What is making you focus on the choke thermostat, with such a low-miles car? Has it been physically brutalized? If it's just the rusty appearance, be advised they all look like that after a couple years of being "cooked" by the heat from the exhaust manifold.