Took me most a decade to cover most variations of 750 engine set ups.
Peels best combo by far was the 28 mm head with 10 CR and 2S cam and 1.5" pipes made into a 2>1>empty Dunstall megaphone with his soup can baffle replaced byan end plate with 1 3/4" hole blown through. First run with 34 single and Boyer, for run out form under response. I left the small 28 mm head lip untouched but further interfered with but crude intruding rubber-fiber material. Its was accidental set up waiting for real Combat head to get done. When I put dual Amals on I had to be more careful on throttle not to just spin on Gravel noticed-appreciated less wrist action to reach speed, pass and satisfy desire to zoom into turns.
Similar happened when I returned factory Trixie Combat to dual Amals, more ease of operation with better throttle response and spunk. Looks nicer too.
Top end can use as much carb as possible but real life get up and go to almost as fast top end, smaller works nicer. Its not a night and day difference though, you do have to twist throttle a good bit to feel the differences. If pure ease of operation and maintenance in maturing wiser man riding and lower wrist effort then single is better deal but for appearances.
