6 pt cage is what you need according to nhra rules, I'm going to run low 10s but chose a art Morrison 10 pt which is a 12 pt cage for chassis stiffness but also my car will be just drag racing.
I imagine the dana is probably between 60-70 pounds difference. If it was Saturday I'd go out and weight my dana. Mine is 46 inch flange to flange so it is lighter by a couple pounds just due to less steel.