Sorry, for some reason I'd gotten the impression that you were perhaps planning an entire Harvard Classics overhaul, probably from your having mentioned putting together a Reading Selections, then tidying up the Index separately.
If you're not planning on reworking the other volumes, then yeah, it makes more sense to just tidy up the Index and reference stuff as best you can. Too bad neither ePub nor Mobi really has a working scheme for inter-book linking yet.
Best of luck with it!
