I have SSBC brakes all around. In the front, they're the same (approximately) as the original Kelsey Hayes 4-piston brakes that came stock on 65-6 Mustangs with an 11" rotor. The rear has a 10.5" rotor with single piston calipers that SSBC scavenged from an ~'88 Thunderbird Turbo Coupe. The M/C I have now is the stock '67 dual-bowl master cylinder (my car is a '65 that originally had the single-reservoir version), also a 1" bore I believe. Although I'm sure that the '67 has the incorrect residual pressure valves, at least for the rear, it hasn't caused any problems that I can identify.
I open track the car and have found that the brakes are adequate to a point. They slow the car well (yes, a determined poke at the pedal locks the tires), but heat up after extended use and start to get a little scary. They'd be more than adequate for the street, but are marginal for track use. Hope that helps.