Disc brake upgrade questions

I never had trouble stopping my 69 Dart w/ 9" drums. It could skid the tires, and evenly, so please tell me what more any brakes could do? Most of the "drums didn't work" cases were due to incorrect maintenance. But, I did overheat them once going down a long gravel road in the mountains where I couldn't use the tranny enough to slow. That is where disks excel over drums (faster cooling) and the reason for the federal mandate ~1974.