I think the larger part of the need in this case is how to redirect for a page that is no longer in existence, as text changes to pages still in existence will be picked up when the site is re-indexed.
301 re-directs would be great if there is applicable content replace the existing. In the case where the information is simply no longer applicable a custom 404 page “Oops, that page isn’t here anymore” followed with either some custom search results displayed on the 404 page, or at the very least a site search box. Make it easy for the user to continue on your site. If you know for a fact that one page or a group of pages are the source of your traffic from re-directs then either replace them with pages that give users the choice of where to go instead, or use 301 re-directs to send those specifics the the most logical destination.