So there are different makers of the 3 types of CB750 K0-K6 4-4 pipes?
I have a set of Yamiya Lotus Root waiting to be used again and one set of their No numbers on my K2.
I also found thanks to a friend that carbs must be jetted different comparing No numbers with HM341. My settings were way too rich for his K2 that needed needles in the middle, main jets 105. My carbs have needles 1 step richer and 115 mains like a 4-1 could have.
(He has a 4th model of old pipes stamped CB750 on another bike, more open like my no numbers using HM300 baffles/diffusers. But the HM300 baffles does not fit.)
I understand those who build a 100% stock build of a K2-K6 that prefer the HM341. I know one guy (retired gentleman) that never should use something else than HM341on his K2 builds.
If nothing new avalaible, I'm sure he can repair an old good set and rechrome it as he did with fenders and rims. I doubt he can use non Honda screws/parts inside, not visible.
His K2 has a very silent idle, not a tiny bit of "clutch" rassle. A real sewing machine.
Not too fast cruising there either....