That was a 1-year only model, ProblemChild has one of those......I have a Clymer manual for the early Z750's which covers this model. It is in pretty shithouse condition, you could say its well *ab*used....
I also have the factory Kawasaki manual for all 750's from 1980 to 1985, including the R1. Send me a pm if you need anything in particular for servicing your bike....