Have you checked the t....oh right.
Remind me what engine this is?
How are you tuning the carb?
What steps have you taken to measure manifold and timing port vacuum?
What size jets you using?
What size power valve?
Fuel pressure/float level?
How are you setting mixture levels?
Any carb will work if it is set up right. It will work even if it is only ballpark!
Changing to another make will make no difference unless by chance you hit on one that is set just right. I prefer the Carter/Edelbrock type (yes they are similar) because I find them easier to work with. But that is more of a personal thing.