E brake help

My 68 and 69 Barracudas are both as you say . I think my 70 Dart was also same.

But IDK how the wheelbase differences might stack up. Barracudas are 108s and the 70up Darts are 111s. I think your Sport is same as Duster; 108wb ..I think my 70 Duster was also same; so looks like 70 to 72 Duster is your best bet for cables, and any A-body 68 to 72 at least for the bracket.
I'm guessing.

But like Charles mill says; to run this type of early cables; the ends are different from yours and will not hook up inside the rear drums..... unless you also swap on the earlier style backing plates and brake arms and probably the struts as well. And the backing plates would also have to match yours as to diameter and width of the shoes.