When I changed the bars on my foxeye to renthals I had to drill small holes in the bars for the switches and levers as they have locating pins on them, I assume that FZ6 is the same , I do know some just file off the pins in the handle bar switches and levers which is a bit irreversible and depending on how the FZ6 bar end weights mount you may need to get renthals ones or find a way to fit the oe ones.
I'm not sure about the fz1 bars as again the locating pins might be in a different position and you're back to the drill holes or file pins conundrum.