Musashi. By Eji Yoshikawa.
My version of Shogun is 927 pages. Musashi is 984 pages. However, the font in Musashi is smaller, and the pages are thinner. (Think Bible-like pages.) The books are about the same size and weight.
Musashi
By the way: The Shogun mini-series with Richard Chamberlain is a good translation of the book. Also, the Musashi movies (non-creative Japanese name: "Samurai I, II and III...) are good too, IF you can find all three parts, in good quality, with English subs. I was lucky on ebay, two years ago. Note: Toshiro Mifune plays a lead role in both movies series. He plays Musashi in Musashi, and Toranaga in Shogun.
Oh, I also have the hardcover version of Stephen King's IT. It's also a little bit thicker than Shogun, as is the first of Salvatore's Drizzt quadrilogies. (I have those in paperback.) My copy of LotR (hardcover) has 1401 pages. I shudder to read that again in paper
edit: And yes, the Eji Yoshikawa books, including Musashi, can easily be found as epubs, and the OCR seems to be very good. However, the layout is crap. I have all three books in hardcover, for years already. I actually read Musashi in Dutch first. It was a gift. (IN DUTCH. WACK. Where "Musashi" is spelled "Moesasji".)