According to my service manual, and "LOUDGPZ" excellent website, the adjustable main needle found in rebuild kits needs to be set at the second clip from the screw head (flat end, opposite the taper) end to match stock jetting. For example setting the clip in the middle, third position from either end would be richer than stock.
However I have a seen a few posts here that say the opposite.
1982 Kawasaki KZ550 LTD