I also ran into the issue of my connecting rod bearings being "out of stock" when I was assembling my kz750 motor. So I found that the 2001-2005 zr-7 used the exact same bearings only the color coding for the sizes was different. They were identical to the kz750 bearings in every way.
Now that I have already finished my engine, I have noticed that Kawasaki has merged the part numbers for the crankshaft main bearings ( The bearings made from 1983-2009 onward were made of a different mixture of metal and therefore had different part numbers) and the old kz750 main bearings were twice as expensive than the others. Now the 1980 all the way up to the 2009 use the same bearing part number.
But if you need a green coded rod bearing you can order the blue zr-7 rod bearing instead.
kz750 bearing sizes and color code
zr-7 bearings and color code
I also had some of the colors missing from my bearings, but if you follow the factory system of crankshaft, connecting rod and engine case markings, its simple to figure out which bearings you need.