Disc brake conversion (70 Dart)

Wow! The OP has 9" drum brakes. If he replaces them with OEM small bolt pattern 11" K-H front discs, he will think he has died and is in heaven. Same for the single piston big bolt pattern "A" body 73 up conversion. Going with the big bolt pattern 11.75 OD 2.75 piston pin calipers and good pads on a 1970 "A" body, he will be afraid to touch the brake pedal. All the calculations and theoretical BS is amusing, but let's get real. For me, as soon as you start with aluminum hubs and aluminum caliper adapters for the street, I'm out. I don't care for the lack of hardness, or the coefficient of thermal expansion of aluminum. I've seen too many aluminum parts fail. If you want to race with that stuff, that's fine with me. You're not using it enough and replacing stuff often enough you should not get into trouble. I have run all of the above, and have driven Porsche's and Vette's and was not wowed by any huge difference in braking. I also have the AR Engineering Viper conversion, but frankly have not felt compelled to swap it for what I already have, yet. I'm sure all the newest wiz-bang stuff works better, but mine will be still be working fine for the next 50 years. To the OP, see if your rotors will clean up, replace the bearings and races, use your calipers for cores and get some 71 Barracuda Calipers and flex lines and have at it. Best of luck. Notice I did not attack or ridicule anyone?