meurigfz750

Hi, all. Hope some one can help my Fz is 1989 and will need replace ment front discs very soon, but it seems to have wrong size front wheel it is a 17 inch wheel. I have talked to others some say it was a model up grade and some say this was an after market owner upgrade commonly using the fzr 1000 front end. Any help to solve this would bevery usefull also any idea where to get cheap (used discs)? Cheers Meurig