Time to visit the children's librarian at your local library and ask for a talk about books that are both age-appropriate and at his reading level. This can be tough. You want to keep him interested, but the things he is able to read are not necessarily things you would want him to read -- believe me. My daughter has always been a very advanced reader and could read a lot of "young adult" fiction but much of it contains subject matter I don't want for her yet.
As for the school list: I would bet that the school is just not going to deal with this over the summer if you call. If you ask the principal, he or she is likely to say, "Sorry, but this is a topic you'll need to take up with the classroom teacher in the fall." If he must read these books, have him do it quickly; make them as engaging as you can by talking with him about them (don't just read, for instance, "Green Eggs and Ham," but read it with him and then talk about rhythm and rhyme in language, find some other more complex examples like the kids' poems of Jack Prelutsky or Shel Silverstein, and so on). In other words -- get through this list and expand on it with him at home, rather than just having him see it as a chore.
When school starts, talk with the teacher about your concerns about his being bored. Keep a close eye on it. Our first school had a reading specialist who not only helped remedial readers but had special weekly sessions for kids who were highly advanced readers -- these kids did small plays, read poetry, etc., with the specialist. It was a good way to challenge kids who were academically advanced but not old enough yet for any gifted and talented program through the school. See if your school has a reading specialist on staff and if that person does more than teach remedial reading and might offer some more challenge to your son and other kids.