My plans for my 69 Dart Swinger 340

I thought the 340 cars came with disc brakes? I know my '70 Swinger 340 came with the K-H 4 piston discs.
Mine in photo, came with power 10" Power drum brakes all around. Last year I installed a K-H Disc brakes from a 70 Dart 340 Swinger. I needed more stopping power with all the new cars on the road today. My car has a nice ride, with a set of SS springs. No air shocks. A light car, with close ratio manual steering, you don't need power steering.