I would take a q-jet over a holley any day! Those small primary bores give great throttle response and fuel economy and when you nail it, those monster secondaries can make great power. The reason most people hate q-jets is because they are a pain to set up properly and the internals can be complicated to work with.
Why do you think your secondaries arent opening? Just looking in the top of the carb and whacking the throttle while in park means nothing...theres not enough load on the engine to cause the secondaries to kick in. This is why most people think that their carb isnt working right, but it isnt a valid test. What kind of mods (if any) have been done to the car? What kind of exhaust system? If you are running a stock exhaust system with catalytic convertor, take the car to a muffler shop and have them check the backpressur of the exhaust system to see if it is plugged up...convertors do go bad and when they do, the honeycomb in them tends to clog up and the engine cant breathe. As far as your vaccuum advance is concerned, there should be a sticker on the at the front of the engine compartment (normally around the top of the radiator area in plain site) that will have a diagram of the vaccuum hose routings.
Now this is a topic that everyone has their own opinion on...manifold vs. ported vaccum for the vaccuum advance. I believe gm used manifold vaccuum on nearly every 305 made...manifold vaccuum is highest at idle and drops with an increase in throttle opening. However, I have found that this tends to give an engine too much timing at low speeds and normal driving and can give them a low speed miss that wont go away with tuning. I almost always set up my engines with ported vaccuum for the advance...it will be 0" at idle and will increase as the throttle is opened up to a point, and then will go back to 0" at higher revs (this is without using wide open throttle)...this allows you to set your initial timing higher for beter low speed response without excessive low speed vaccuum advance. Either way you decide to go, you need the vaccuum advance...its only purpose is for fuel economy...it is inoperative at full throttle.
Sorry this is so long...hope it helps.
375hp 78 Chevy truck
77 Chevy Nova
95 Chevy Lumina 3.4L
and building a 78 Nova