You would need to replace the rear axles and brake rotors (drums?), as well as the front hubs (and possibly calipers depending on how the conversion was done in the first place)?
Alternately you could just remove all of the above, take them to a machine shop, preferably one that specializes in driveline stuff, and get them to plug-weld the Commodore stud holes and redrill to the pattern you want, which I'm guessing would be either Torana or HQ stud pattern?
I believe it's illegal to have multi-drilled stud patterns although I'd have to read up on that again to confirm?
Your third option would be to find another Torana owner who wants to swap with you, but having a 9" diff complicates things, you'd have to find someone with the same length and spline-count axles with the same size bearings, or just swap complete diffs over?
Edited by Bigfella237, 08 April 2015 - 01:33 PM.