Hinemoa's story is now/not available for proofreading
Well, you'd better hurry if you want to go to Project Gutenberg's Distributed Proofreaders website to help proofread Rev Henry James Fletcher's Hinemoa: with notes and vocabulary. (Why bother to mention it? It's the first book on the DP site with Te Reo Māori claimed as the primary language.)
So far, it's looking like it will have the fastest first round proofread cycle I've ever seen on the site of anything I've uploaded (not counting a book that was around 5 pages or so I previously uploaded).
Or, if you don't want to proofread it, you could just download the PDF scan of Hinemoa instead. The whole book comes with a glossary (the book appears to be pitched as a textbook for English-speaking learners of Māori language and culture) and some sort of quick summary of the story in English; methinks one would find the entry on the Hinemoa story in the 1966 edition of the Encyclopaedia of New Zealand also useful.
(It's not the only other book in PG or DP that I can find that's in Te Reo. You'll find Edward Shortland's Maori Religion and Mythology floating around DP at the moment; it doesn't claim Māori as the primary language. That appears to be the only other one I can find right now on either website, however.)