sickkittens - replacing content shouldnt be a big deal as long as its relatively the same type and still meets the LLs rules - although I tend to favor the idea of just 302 or 404 till we know whats going to really happen as it takes a heck of a lot less work (and Im always for that)
as far as the sites where some are and some arent - hopefully they are in their own little subdirectories and you can add a htaccess to 302 or 404 anything below those directories