I don't have any easier or better solutions for the index. However, I agree, scan the index in leaving the hard-text page references. In the legal field, we need to have electronic versions of depositions all the time. When the hard-text is scanned or however it is imput, the hard page numbers are included. In those instances where the page numbers are not available, the index would still be useful otherwise.
Software provides the best example of how an index comes in handy.