TOPIC:

Will the wheels from a GPZ 550 fit on a KZ 750?

Consider looking at partzilla or Kawasaki.com and see if the axle sizes are the same on both models. What years are we talking about? If the axles are the same, you're off to a good start, then it's just a matter of finding/making spacers to align the sprocket, rotor and caliper! Easy Peasy!

Just FYI, there are 3 different types of GPZ550's, each with different wheels.

81 had 7-spoke.
82-83 had 5-spoke.
84-85 had a sort of 3-spoke design.

Look at the front diameter too. The early bikes used a 19" front, but moved to 18" in later years which would be more difficult to adapt.

The easiest way to determine if there is a chance of fitting is to compare the front and rear wheel bearings, If both bikes use the same bearings then the axles are the same diameter, then all you need to worry about are spacers.