Yep, everything CatFish said is dead on too bud.
I've heard a few people say they've had good results when dealing with this company. They were intent on having the Qjet rebuilt for factory correct muscle car restorations. Just in case you don't feel comfortable rebuilding it yourself.Quadrajet Rebuild Service
I've rebuilt about 20 or 30 in my day, but that 25-30 years ago. The last one I did was on my 72 Chevelle in 1998 and I ran that one for about 1 year and found a smoking deal on a good Holley 600. I could tune the Holley much easier at the drag strip, so I never went back. I've still got a few Qjets in my big carb basket on the parts shelf, but they're just sitting there collecting dust.
With a stock 305 though, you're going to be better off sticking with a stock Qjet or one of the small CFM Holleys. Holley recommends 390-465 CFM for a stock 305, which are $540-$620 depending on which you go with. I've got a 600 Holley I'm going to try on my 305, but I have a feeling it's going to run way too rich and I will be rebuilding one of my old Qjets for it.Holley Carbs