Once you start swapping wheels you are going to have to align the chain and sprockets.
Usually with more modern wheels an offset front sprocket is often needed and very likely the rear sprocket carrier will need shaving to bring the chain run in line.
As an example when fitting a 5.5 inch ZXR750 rim (180 tyre) to a Z900/1000 ( the widest without frame mods ) the front sprocket needs an offset of 5/8ths and the rear carrier shaving by 8mm.
This is to allow the chain to just clear the inside of the frame and the edge of the tyre.
Obviously for this width of rim a wider swingarm needs to be used.
If using a Suzuki GSXR or Bandit arm these are slimmer at the pivot than the KZ frame so they just need spacers to take up the width and the spindle size differences addressing.
You may also have to modify the rear footrest and exhaust mounts as the wider arm is likely fo foul them.
If you want some pointers and ideas of what you may be getting into have a read through one of my current build threads over on the ZOWNERSGB forum. -
Double the troublezz. AMA style Racecrafters Z1000 and Moriwaki Z1R Turbo. - Z1OwnersClub GB