1967 Dodge Dart convertible spring relocation mini tub axel width

So I am mini tubbing and relocating the springs on my 67 Dodge Dart gt convertible. I am using the us car tool kit and will be ordering a brand new 8 3/4. What housing width flange to flange and what wheel and tire size have everyone used? I am planning on getting disc brakes for the rear also. And what's the best differential locker to use for a street hot rod? Thanks for the help this is a great site.