Brake Fluid Leak

[gschroeder]

I have a 1970 CST10 with factory power brakes. Just finished the restoration, and noticed there is a small amount of brake fluid leaking between the master cylinder and brake booster. Fluid appears to be coming out of the bottom of the master cylinder and running down the brake booster. No fluid is leaking from the master cylinder cap. Brake seem to work fine except for this small leak between the master cylinder and brake booster. Do I need to replace the master cylinder, or both the master cylinder and brake booster? I see rock auto offers a master cylinder rebuild kit, but it cost almost as much as a brand new master cylinder. Thank you for your help.