I have the correct 66 Quadrajet on my 427. All I did was put on a choke thermostat (spring) that seemed to be the correct tension and then did the finishing touches to fine tune it by bending the rod from the spring to the choke linkage so it had some tension on the choke flap.
The choke pulloff should open the flap slightly (I am guessing about 1/8") when you start the engine. I think there is an exact spec for how much it should pull open on startup.
After that, just make sure it's wide open (vertical) when fully warmed up.