Need rear axle change over information SBP to BBP

I am going to do the KH brake rotor swap so I can get to BBP.

I would like to know what my options are to change my rear axles to BBP. I am running the stock 7 1/4 1968 A Body rear end in my Barracuda. Can I change the axles and brake drums? What about the backing plates? What years of cars would fit?