Hi Ed, see my post in this link,
www.kzrider.com/forum/4-electrical/62041...lator-rectifier-info
The later KZ ("J" models and later 750's)would be the same as the GS because the RR output is fused on it's run to the battery so you would delete the brown and connect the + from the RR to the red/white wire in the original loom for the RR. Earlier bikes would also delete the brown and the red from the RR would go to the battery side of the starter solenoid or direct to battery + terminal (ideally through a 30a fuse especially if using a lithium battery like an "ultrabat")
Correct me if I'm wrong, but the diagram in the other thread shows a 6 wire R/R. What my diagram references is a 5 wire R/R, as installed into a 1976 KZ1000.
Power from the R/R will feed the bike load, as well as charge the battery using the normal wiring on the bike. Mind you, if the old wiring is crusty, it should be replaced. And if doing so, it might be best to shorten up the wire run.