'73 Swinger brake drag

Hey guys, looking for some advice. I recently picked up a '73 Dart Swinger as my first classic car. It's got manual brakes, disc front drum rear. I believe the previous owner changed the original front drums to discs, but I don't know that for sure.
When I took the car to get it inspected, the mechanic warned me that the brakes were dragging and would eventually burn out the rotors, but I wanted to try and fix it myself.
My Father in Law and I replaced the calipers in front, changed the soft lines and brake fluid, and bled the brakes, but they still seem to be dragging. I took it for a quick 2 minute drive around the block, and the rotors were already hot to the touch.
The master cylinder looks like the right one, 2-chamber "small front, big rear" style. What should I look at next? Proportioning valve? There's no way to adjust the calipers/pads so that they have standoff from the rotors, is there?

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