Performance means different things to different people. Please, supply your definition.
The bore size for all the 750 carbs is 28mm. So, they all flow the same amount of air, and have the same power capability.
The carbs with accelerator pumps have the cabability to run at better economy as they can run leaner in the low ranges, and still provide good engine pick up from low speed.
Parts for the 77/78 carbs are harder to find than with earlier carbs. These carbs require more creativity to make work around the limitations of press in slow jets, and lack of needle height adjustment on some of them. They also have an accelerator pump that adds mechanical complexity.
The older carbs run richer overall to get throttle response. In that sense they can be described as "sloppier". More of these types were made so parts are easier to find. Slow jets are screw in and needles can be found with different tapers and adjustment height options.
Assuming they are both properly tuned to the bike's engine, intake and exhaust characteristics, at wide open throttle, neither carb will show an advantage. For overall street driveability, economy, and twist grip responsiveness, the 77/78 carbs ought to have the advantage.
Some might call this a performance advantage.
Others might say that the "sloppiness" of the older carbs, gets their engine running "well enough" for them to enjoy then on the street. And, that's all the performance they need.
What are you seeking?
