The K-H discs are great, BUT probably the weakest point is the THIN rotor. No way to fix that either. They also don't need power brakes. My son was autocrossing his 383/4sp Barracuda with them until he cracked a wheel center on the home-built 15x10 SBP wheels. That was the only reason we switched to big bolt. Rotor size has nothing to do with clamping force, but with cooling ability.
For what it's worth my younger son's 67 Dart convertible has 73-76 manual discs with a 440 and four speed. I blew the left front tire at 70mph around a sweeping right hand turn on 101 heading into San Luis Obispo a few years back. The car dove left immediately, but I was on the brakes HARD (too much adrenaline to do anything else but lock them up). I was able to keep the car on the roadway until I was going slow enough that the shoulder didn't scare me anymore. The brakes never faded or gave up. The rears are 11x3" drums.
OH, one other thing. The myth about big block a-bodies not being to handle was based on the junk that passed for tires in the 60s. Had no dip or dive in that panic stop.