this is a really complicated job but it can be done and here is a the problem is the suspension after you narrow the rear axles you will have to go with coilover suspension here is place where you can buy shorter axles and the correct coilover to get the job done also ron Lummus is the king of the narrow rear end conversion you can try to contact him thru the web page:
http://www.ronlummusracing.com/Race_store.htm