carbs from a zephyr 750, 29 smooth bore, RS34 will fit but will be too big unless you have a big bore kit, cams, high comp and then that will pretty much be race application only. all of the carbs will require different intake boots.
Those numbers on the carburetors probably won't mean anything to most folks.
For physical fitment you can probably use the carburetors from any KZ750-4 as they all used the same carb holders & airbox ducts.
Most of them thru 1983 had Keihin CV34s. Some had Mikuni BS34s >> 82 GPz 750-R1, 83 750-L3, 83-85 ZX750A & 84 KZ700.
Not sure what carbs the KZ750N Spectre, KZ750F & ZN700 Ltd Shaft had, but the carb holders & ducts are the same, so these should fit as well.
Also, you should be able to use the carburetors from a 1999-2005 ZR7 or ZR7S (ZR750 F/H models). These have basically the same engine as the KZ750. Someone at a KZ650 site installed a set on his 650, so it shouldn't be a big problem on a 750. Also, I would assume the stock carburetors from a 90s Zephyr 750 would work as well (ZR750 C models).
All of these ZR750s noted are air cooled w oil cooler (not liquid cooled, no radiator) & engine numbering is KZ750EExxxxxx.
On the 650 he had to modify his airbox. shouldn't be necessary on a 750. He also had to make the carb holders work. also not a problem for a 750. However, you may need to rig up a way to operate a choke rail which is what he had to do. he connected a knob or something. I don't think ZR750s would be that hard to adapt, but for simplicity I would try to find an 80s vintage set of carbs. It depends upon how industrious a guy is. The same type of carbs as stock would give the added benefit of spare parts.
It's getting difficult to find a decent set of rebuildable CV34's for a half way reasonable price. I've rebuilt something like 6 sets for flipping but guys on ebay want crazy money these days. You can get some VM24 KZ650 carbs for dirt cheap so if this is just a runner project, that may be a reasonable way to go.