Stick with OEM....many of us on the forum have done it. They are NOT universal
Link below: (Part# 43020, and you may want to pick up #92055, and other small bits)
2005 Kawasaki Ninja ZX-6R ZX636C FRONT MASTER CYLINDER Parts, 2005 Kawasaki Ninja ZX-6R ZX636C FRONT MASTER CYLINDER OEM Parts - BikeBandit.com
Edit....didn't realize you plan to rebuild the calipers? Either way...stick with OEM, or buy a whole caliper as a set to bolt on.
Link below: (Part# 43020, and you may want to pick up #92055, and other small bits)
2005 Kawasaki Ninja ZX-6R ZX636C FRONT MASTER CYLINDER Parts, 2005 Kawasaki Ninja ZX-6R ZX636C FRONT MASTER CYLINDER OEM Parts - BikeBandit.com
Edit....didn't realize you plan to rebuild the calipers? Either way...stick with OEM, or buy a whole caliper as a set to bolt on.