help with some jets

I have a 1983 KZ750 LTD that I bought from a guy a little while back. He put Mikuni BS34 carbs on it that he said came from a GPZ 750.
I am going to upgrade the exhaust to a V/H 4 into 1 and needed to know what jetting size I will need for it. I also noticed the needle jet has a clip on it so does it need to be adjusted too.

let me know and thanks,

max

If you have the stock airbox on it and the pipes have a street baffle in place, I would guess you would likely need to only go up maybe one jet size on the main and pilot above the stock jets. That's just a guess.

For needle, start with stock and see how your low end throttle response feels.