Carb for 340

Mostly street driven. I've been spending the last year fixing everything on the car. I have it running pretty well though but it feels like it should have more power than it has. The carb on there is either a 600-650 CFM old school Holley. I'm going to put the new carb on there and have it dyno tuned to get it running better than it is now.
You should find out what you have now. Model # is on choke tower. A few common examples: 1850 600 vac, 3310 750 vac, 4776 through 4781 are dp numbers 600 to 850. If you have a 4777 650 it can be made into a 750 with one of these: http://www.summitracing.com/parts/pro-67100c