I am running a 1088cfm Pro-systems Dominator on the old 65'. Which carb you use will just depend on what you want from the car. The Holley HP series carbs are great for performance, but I still favor the Quadrajet for most dual purpose cars. Stay away from the Demon stuff.
You can buy a brand new Q-jet from Edelbrock. These carbs are made from the same tooling that Rochester used. Stay away from any kind of reman carb, as you will almost certainly have issues of some sort. Don't get rid of your origional carb either. I wish I had the origional Carter that my dad traded in as a core 25 years ago.
The Q-Jet, correctly set up, is a very good performance carb for the Pontiac. The carb flows 750cfm, (the 455SD flows more) and is easily tuned to provide excellent response. We've been racing Pontiacs with Q-Jets since the mid '70s, and the carbs run great on the track and the street. They tend to get a bad rap because a lot of people get them tuned and set up way out of whack. Set the carb up initially to its stock jetting secs, replace the float with a new NitroFill float from NAPA, and set the float level to 3/8". Run 3/4 turn windup on the secondary airvalve and verify secondary rod hanger height at 41/64". This will get you a very good baseline setup, and will provide very good performance.
If you want to go with a Holley or a BG, these carbs also run very well if you get a good quality carb (don't go with the cheap 4160 vac sec carb with the secondary metering plate and chrome finish). However, these carbs are square bore carbs, and cannot be used with your stock intake. If you swap out the intake for a Performer RPM you can take advantage of a good HP series Holley or a Speed Demon series BG. We've had excellent success running these on the street.