Easy,
I run a QF SS-750-AN (DP)on my mild 340. It has annular boosters which QF says it's actual cfm is 735. It has adjustable secondary mechanical linkage which you can delay either 40% or 60% with just a linkage swap to help tune the secondaries. The annular boosters gives better throttle response versus my other two DP carbs with downleg boosters. Call the guys at QF and ask them for their suggestions.
You might want to add some more info about your combo unless your already sutup for a DP.