Rear Master Cylinder Upgrade 1978 KZ100

Is there an aftermarket replacement or a suitable upgrade to the rear master cylinder? I would rather not rebuild my 37 year old one and think someone has probably already figured this out by now. I am handy and can fabricate adapters and such if needed. I am looking to benefit from the wisdom of someone whom has made this work. Thanks!

I would just rebuild the old one.It may be 37 years old but it was well designed and built for what it is. Unless youre changing the complete brake system,why upgrade just the master cylinder? This master cylinder was designed to go with this caliper on this disk etc. Change the pads,change the hoses maybe.Other than that,keep it stock or chage the lot.
Thats my tupence worth.Good luck.

In stock now at Z1 Enterprises: www.z1enterprises.com/ItemDetails.aspx?i...00&item=KZ1000MCKIT1