Many Quadrajets used two choke pull-offs dating clear back to the 1971 Buick units.
One will be a "primary" and the other a "secondary".
The primary pull-off typically unloads the choke and dampens the air flaps as it's secondary function.
Up until 1979 the front pull-off was the primary and rear the secondary, then we started seeing rear pull-offs showing up with two links and they because the primary pull-off. On some carburetors there will be only one rear pull-off since it performs both functions.
Your 17085000 should have a rear pull-off that serves as the primary and a front pull-off that's secondary, nearly as I can remember.
It will require the rear pull-off if that's the case and the front becomes optional. Probably not a bad idea to use both in case on fails, but the primary pull-off needs to be working as it provides the secondary function of dampening the secondaries to prevent stumble/bog going quickly to full throttle.
As far as the fast idle solenoid on the drivers side front, they were used with A/C equipped vehicles and come on with the A/C clutch to prevent the idle speed from falling off too far. If you have A/C you may want to use one........Cliff
Below is a pic of a later model carburetor that uses the rear pull-off as the primary pull-off. It shows both links, one up to the choke and the other to the secondary air flap shaft linkage.
