I could be wrong, but I don't there are any useable paint codes from back in the day. Different types of paint were used back then & several different layers were applied in some cases. There are Lubritech paint charts floating around the internet, but that company isn't around any more. Search the internet for Vintage Kawasaki paint codes Lubritech or something like that.
Like everybody says there are no code to mix paint from. If it is only the clear that is peeling you might look into just clearing it again. I have had some success doing that on original paint 73 - 75 Z1 tanks. I am not set up for painting right now, just selling paint.
Lubri-tech was bought by Color-Rite, but they only go back to 82 for most makes.