Anyone have any experience with a cruise control system in the early 240s?

I just grabbed a whole unit out of a '80 that was in the junk yard. (Same car that it will be going into. It was even a manual transmission like mine.)

I got the speedo out of the car as well. It looks like (not 100% sure) that I can take the sensor out of it and put it in mine. At least, I sure hope so. (Donor car was a sedan, mine is a wagon.)

Anyway, I don't know much about these early cruise control systems.

Basic questions:

How well does the system work?

What are common failure points?

Anything I can do to the system to improve it, or prevent any issues while the system is out of the car?

Just how important will my speedo's accuracy be? (The needle bounces a bit.)

If anyone has any schematics that show how this mess is suppose to be hooked up and could give me a few details about the wiring, I'd appreciate it. (I didn't take notes, as I had to pull the thing quickly.)

Thanks as always.
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If you listen to the radio in Portland, OR, you may know me as 'Portland's Favorite Soul Brother!'