Aftermarket rear axles is the easiest and it isn't much more than having a set of C-Body axles re-sized. The original sbp axles can't be drilled because of the access hole and they don't have a large enough flange to be safe with the larger bolt pattern anyway.
The front would depend on what you want to spend, aftermarket setups usually run around $800+ but you can find everything you need (upper control arms, spindles, rotors, dust shields, etc.) from a 73-76 A-Body for around $100-$200 depending on who has it, you can also get new brake pads, seals, hoses and bearing at most part stores without having to wait on shipping. The rotors are also the same as most 73-85 Mopars and easy to find.
