Disc brake kit swap from 7.25 to 8.75 possible?

Hey guys!
Just got myself my first mopar yesterday, a 1964 Dodge Dart GT, went 50/50 with my brother. Rebuilt 318, ported heads, dual plane intake, 650 cfm, rebuilt prepped 727 and other candy. But it has a piece of poo 7 1/4 rear with a bent pinion axle:(
It has a rear brake kit and I wonder if this kit can be swapped to a 8 3/4 or even a 8 1/4 rear?
I have only seen pics of the car because my brother lives in Sweden and I live in Finland, so I can't answer any questions about the axle yet.
Author: Turbotarzan