You might try the free trial of VideoRedo TV Suite. It can import dvd video directly and has a couple of different tools for correcting audio/video sync. The easiest to use is the Quickstream Fix tool. I don’t think you’ll be able to keep the original menus…but could be wrong. I don’t have the full TV Suite, just the original VideoReDo Plus.
Womble Mpeg Video Wizard DVD is another mpeg editing tool with a similar type of audio/video sync correction. It has a free trial as well.