Nissan Vehicle Operations are probably the only folks w/ an accurate answer. If only 240 made given what % manuals are built at now overall, I would say simply 'not many'. Likely a higher % on Heritage than general Z production, but even that would be only dozens.
I heard it is not so easy getting exact production numbers from Nissan for some reason. You would think when they produce a limited run model it would be simple. Almost bought a 24 Heritage. I really like the front end look with the flat black graphics.