A mean cam and you will suffer with any carb. Carbs depend on vacuum signal to operate and you will need to compensate by cranking up idle speed, usually by drilling holes in the throttle plates with a wild cam.
That aside. Smaller carb is better. A huge carb will slay your throttle response, idle and basically everything but flat out racing. You will hate your car if you need to drive it on the street. It will have not bottom or midrange and hesitate at every light.
The DP is for flat out racing. A vac sec is for everything else. With a DP, you can floor the car at a standstill and both throttle plates fly open but the air looses all velocity. The dp compensates by throwing not one but two shots (hence the double pumper) of accelerator pump down the throat of the carb but in practice it does not do that well and the car still wicked bogs. With a vacuum secondary, you can only throw the primary open at once and the engine controls based on vacuum requirements alone, when and if the secondaries open. Much better system.
I second the holley 670 street avenger. One of the best carbs I have ever seen. Has every bell and whistle you could ever want on a carb and even the factory settings are almost right on. But lets say you have a 347. You probably wont spin past 6000 rpms so 347X6000/3456 = 607 CFM. A 570 Avenger would be enough if it is only a streetcar and the throttle response would be insane. I have 3 carbs: 570 SA, 670 SA and 600 DP and the 570 vacuum sec takes the prize hands down. The 670 if you rev past 6K regularly but you will sacrifice some lower end.
Just some food for thought.
