Just remember with engines, whatever goes in must come out, so if you open up the intake side, you must open up the exhaust side---visa/versa too. Also, when doing the intake/exhaust, you HAVE to readjust your carburetor or the air/fuel ratio will be off. That's why with todays FI the computer does this for you and your engine is all good, but do this to a carbed vehicle and you got valves burning if you don't readjust things.
The best place for a Quadrajet Carb is in the trash. They're good for restorations and when new, they did fantastic with running, but when they get old and warped, there's just not much you can do with them.
Get yourself a good Holley Carb around the 750 range and do rejetting and other fine tuning, and you'll get lots better results, plus you'll always have parts available.
For the Distributor, a "retune" is replacing the old weight springs with lighter ones to let the distriburor rev up quicker for advancements in the timing degrees. Also, manually advancing the distributor helps with milage some, as with most big block engines, they really like more timing than what the factory set them at.
To really wake up an old big/small block, along with headers and carbs, a good conversion to "electronics" help. Get a Electronic Distributor kit to tie into the old wires, along with a new Accel, Mallory, or Holley Coil for hotter sparks. Speaking of sparks, change out the stock plugs and go with some Platinum Plugs OR E3 Plugs.
I run E3 plugs in my Craftsman riding mower(24hp) and my Stihl chainsaw(ms310) and I've noticed easier/faster starts, better RPM smoothness at idle and high RPMs, and definitely using less fuel for longer run times, and the oil is staying cleaner, longer in the mower.