One thing I've learnt about replacing audio tracks from different sources is that doing the replacing without the video can be extremely time consuming to get it as accurate as possible, without the video as a guide to synch them together you don't know if the source or destination have dropped frames that can put the sync way off.
Which is why when I finally do my own DVD set with audio from the Definitive LD's and video from the German THX LD's I'm going to have to undo the 3:2 pulldown on the captured Definitive LD set so I can match the frames up with the captured THX LD set to then save the Definitive LD's audio and use it with the THX LD's video.

I've got the first 3 seasons of the ReBoot CGI cartoon on dubbed Russian DVD that I'm going to synch up with the audio from my VHS's sometime. Another future project I want to do is get hold of the French DVDs of Insektors and remaster them with the British audio (they dubbed it round the world, each country having their own voices, names for the characters and in-jokes that only people in that country would understand)