Is this any good or will it work for my 73 duster?
Just to throw another option in for your thoughts...see what local pricing might be on a complete B-body 8-3/4. If complete, you would get big bolt pattern axles and bigger brakes.
You can run a B-body rearend in an A-body if you change the spring pad spacing. You can either get wheels with different backspacing or get the rearend narrowed.
My '69 Dart had a B-body rear in it when I bought it. I'm going to get the rear narrowed a bit to fit the wheels/tires I'm going when it goes back together.