Replacing rear master cylinder

I have the same problem that KF4ZHT posted about in regards to rebuilding a 14mm rear master cylinder; no kits available. I also do not want to mix and match kits to make a working kit and currently the one I have is leaking fluid around the piston.

I have a 5/8 rear master cylinder that I am sure came off of a KZ1000. Z1 has kits available for this unit.

Before I buy the rebuild kit and replace the 14mm with the 5/8 master cylinder I wanted to get some opinions. Does anyone think that this would be too big of a master cylinder for my KZ650?

For reference the brake system I'm using came from a 78 KZ650 SR which has twin pistons in the rear caliper.

i think thats a single piston caliper

I thought it was too, but I took it apart last fall to rebuild the piston and found one piston on each side of the brake disc. Of course my definition of twin piston could be wrong :lol: