A few years ago I had the pleasure of working on a Burns Family Studio film called Pendragon: Sword of His Father. This was the first major film from this studio and they consulted with me extensively during production. A conscious decision was made to bite the bullet, replace almost all the location dialog, and (re)build all the sound in post.
This is a video I made in 2008 just after the completion of Pendragon. It will give you some idea of the audio post production process