One other thing. I have done more Ford work than GM, but there should be some kind of heat pot setup for that choke.
The first of those type chokes pulled air through a heat pot on top of the intake around that spring to cause the choke to open as the engine warmed up.
The electric was to let the choke pull off faster.
Some engines, not necessarily GM, had the feed for the choke coming off the alternator so that it only opened faster when the engine was running.
You don't mention where you are, but down here in Fl. I often loosened those three screws and turned the cap until the choke was locked out in the summer time.
It might be a little weak for the first couple of minutes in the morning, but not bad.
Instead of hooking up the choke in the winter, I installed a manual choke kit in every vehicle I owned.
It was a black cap that replaced the cap that is there now, with a hole in the center with a shaft coming out.
You hooked an arm to it, and a choke cable to the arm.
It had several advantages. To use it, you depressed the accelerator and pulled out the choke knob.
This put it on fast idle with the choke closed.
If you pushed the knob in without touching the accelerator, the choke blades would open but it would remain on fast idle until you depressed it.
Came in handy on my truck with the PRO winch. I would push down the accelerator and pull out the choke.
Then release it and push the choke back in.
That would open the choke and keep the engine idling fast, which made reeling up the winch cable faster when I was by myself.
The kit looked like this.
http://www.northernautoparts.com/ProductModelDetail.cfm?ProductModelId=25765
Not sure if that one will fit yours.