I sort of remember that system, and your research is correct- - - -it was a very early emission control system which only allowed the vacuum advance to operate at certain engine temp and gear selection situations. I'd suggest simply disabling the whole works- - - -it was pretty much a bust, and it made the already puny 307's performance and gas mileage suck even worse!

I was running a shop in California in the late 1970's, and it was a constant hassle to keep up with all the exhaust emission regulations. Back then, cars in commiefornia had to pass an annual emission control inspection before license plates were issued. Getting that "state inspection station" license involved making some under the table bribes to the state "clean air" people, but the shop owners who got the license got rich on the inspection fees! (No, my shop didn't qualify!)
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!