B-Body Axle?
I can't say if this would be a good choice or not. I can tell you that my rear axle turned out to be an "A" body rear axle despite the casting numbers. I can share this with you. You will need the larger u-bolts and shock mount plates as the axle tube will be larger and the 7 1/4 stuff won't work. Also, be sure to keep the stock e-brake cables to retro into whatever you choose to put in the car. On the surface, you could probably move the spring perches and make it work with the correct offset wheels but unless the charger rear axle is free, I would probably try to find an "A" body axle. The change is hard enough if everything is right!
Good Luck with whatever you decide, DR:coffee2: