I dug more into the choke this morning. It's just weird.
There is a teeny, tiny bit of spring tension, coming from the linkage on the outside of the carb. I can't decide if the spring there is supposed to be wound up one more turn or not.
No matter what I do, the choke won't close more than about halfway. I don't know if this is temperature? It was 50F this morning when I was working on it. Or, is there something wrong with the choke?
Also, I think the accelerator pump may be bad. When I twist the throttle to simulate pumping the accelerator pedal, I have to twist pretty fast to see much spray. And even then, it's just a few droplets. And when it's idling right after startup, I can nearly kill it by pressing the foot feed down fast.
Rumor (AKA USPS tracking) has it that a new-to-me functional carb is coming my way -- old carbs are cheap on eBay. Now, I can have one to run the truck and one to play with.