The favorites of the boys in my house about that age:
DS 1 Horatio Hornblower, Treasure Island, The Lord of the Rings, To Kill a Mockingbird, GA Henty , A Connecticut Yankee in King Arthur’s Court
DS 2 Where the Red Fern Grows, A Long Walk To Water, The Great Brain, the Art of Keeping Cool, and any of the short story books by Patrick McManus. I don’t know if CM would like them but they are hilarious and have such fabulous vocabulary but you either love them or hate them and you probably have to have at least some experience in the woods.
DS 3 is currently 13 but likes The Art of Keeping Cool, The Lord of the Rings, and the Redwall series, Dr. Jykell and Mr. Hyde, Beowulf, Swiss Family Robinson