I was confused about the model name you mentioned, as GT was a two stroke series by Suzuki. But after checking I think you are talking about 'Kawasaki Z550 GT', which is a shaft driven KZ550 or GPz550, depending upon the market/country and year of manufacture.
So, in addition to all the above comments, you have to seriously check the availability of spare shaft drive. The actual engine (KZ or GPz) used is also important.