Will KZ 900 wheels fit an 80s GPZ550?

Brake issues? What else? I suppose a set w discs is simplest . Are widths very different? Axle diameter?

What exact 550 is it? Disk width, diameter & alignment could be issues. If the 900 has a larger axle, different bearings might be used to mate the wheel to the 550's axle, assuming the needed bearing size is available. See wheel bearing charts at Dan's mc repair course. Kawasaki.com, csml & partzilla etc have bearing part numbers.

yeah I'll need to do some research. I can't seem to readily find GPZ 550 specific wheels anywhere, but some Lesters for a KZ 900 were on ebay. I shoul probably just start planning a fork swap to something more modern and solve a few problems at once (brakes, modern tires, better suspension, better looks etc.) Perhaps a Ninja 500 fork nad wheel swap,. Wondering about adapting a similar wheel to the existing swingarm, but againI should just do some research instead of asking vague questions here.
Thanks for the thoughful reply and I really do appreciate a lot of things I've learned here or been inspired by from y'alls projects. Thanks for all of that if I've never said it.
Y'all should probably hear it more than you do.

What exact GPz is it? There were a coupe of KZs & a ZX.

Thinking 83. It has a much larger fairing that the mirrors are mounted to. Has a stem welded to the steer tube to support it. Unitrak rear swingarm. Maybe 84? I've had a couple of 82s and this one is similar in all but the fairing.

Thats an 82 or 83 with a 84 or 85 front fairing . Looks like a 84-85 wheel on the back too . Is that a three spoke on the rear looks small . It should have a 5 spoke like the front .

Front fender from a 84-85 too .

Should have the little fairing like the one in my aviator

I might have a rear wheel for that .

Rear is 5 spoke. Cleaned up what's left of the sticker and it says 82

Front wheel took a hard hit , so that's what started all of this. The one I have out in the shed is completely missing it's front wheel, so I have two rear wheels and an extra drive hub or two.... So, back to looking at front wheels while I try to piece together a complete rack of carbs and see which motor wants to run.

Well keep at it .If you have 2 you should be able to get one together . Ill look around and see if maybe I have one