340 Full throttle hesitation

For your app. & that price range a 750 edelbrock AVS style carb. You have the AFB style carter on there now don't know what cfm it is though. The 750 will give most over all power but a 600-650 will have the best throttle response. I had a speed demon 750 on my old 340 & it worked great! But I also had 4:10's & 3800 stall converter,so it was matched well. Make sure it the AVS style (has adjustable secondary air valve) carb whole lot easyer tuning out the secondary bog then an AFB style.