Welcome to the forum!
I had a 750 Holley Vacuum secondary carb on a 350 engine that was slightly milder than yours and removed it for a 670 Street Avenger. I got the improved low speed drivability that I could never get with the 750 but I could really feel a loss when I spun the engine to it's 5500 redline. Given that background I would have to go with the 770 Avenger for an engine built like yours.