To start -- i don't have any... but what symptoms are you experiencing that make you think you need to change them? I was thinking I needed the same repair -- my carbs are clean but the bike stalls at idle in gear. By the way, I have a CB400a.
I think I got a good pair that came off a set Keihin carbs on a CB 350. They're attached to the slide and needle jet. If you're interested I'll sell them for $20 each plus shipping.
try cyclepartsnation.com they have alot of NOS parts, their parts prices aren't bad but the shipping costs are very high. but when you gotta have ya gotta have it!