What front disc are these?

Those are the "Slider" type single piston caliper.
Most likely 73-76 A Body disc brakes.
But without me looking at a picture of your actual spindle (knuckle) they might even be off an Aspen, Volare, or other body style car.

No, brake pads don't "clip" into the caliper piston on a brake system such as what you have.