67 cuda rear end swap and front disc brakes...please help

So im new to this...im looking for the cheapest way to switch my rear end to the 4 1/2 bolt pattern in my 67 cuda...then of course the front and convert the front to disc brakes..they dont have to brand new ...ive been told a 73-75 dart 8 1/4 rear would be a perfect match for my 360...

please help

thanks aaron