What kind of brake calipers on my ‘71 Duster 340?

Not sure if available at NAPA or ???, but back in 79 or 80 on my 73 340 Duster, which sat a while, I got caliper rebuild kits - basically new pistons, inner o-rings & boots. Got (at NAPA) a honing tool (correctly sized for calipers) that goes into standard hand held drill (variable speed drill is best) lightly honed bores, etc. The hardest part of the job was getting the new pistons back in the bores & installing boots. Consider keeping & rebuilding what you have, most likely better metallurgy & quality than new ones. Thoughts; disassemble, inspect, bring old piston with you to check size of new in rebuild kit. Sandblast or glass-bead old calipers = without seals or boots place old pistons back in bore, seal outer edge of piston to bore with blue goo or caulk, to keep out media. Get high heat caliper paint, perhaps Eastwood might have "metal colored" caliper paint. After calipers are; cleaned/media blasted, bores are honed, new parts (oh, be certain to get new bleeder valves...) installed, paint prep done, tape off boots & blenders then paint. Tip = use a little anti-seeze on bleeder valves, keep away from tapered end of bleeder so as not to introduce anti-seeze compound into fluid cavity. Doing this last step (anti-seeze) will do two things: 1-help prevent valves from breaking next time you bleed and 2-prevent false bubbles, in clear hose on bleeder when initially bleeding, from weeping in around bleeder to caliper surface. A bit of overkill but worth every extra "moments" taken. Have fun.