Hello, if you haven't already, first you should look at the College Board website to familiarize yourself with the types of questions covered in the SAT World History test.
Second, you should probably take a look at some of the AP World History threads and see which review books people consider good for review -- REA, Crash Course, Princeton Review are all mentioned. The material people are studying for AP and the SAT tests are very close.
Having to read a world history textbook seems like overkill, but if you feel the need to do that, you should do a quick Google search for AP World History textbooks. One popular one (used by my daughter's AP World History class) is Stearns et al., World Civilizations. I cannot recommend it, however, because it is thick and not a model of clarity. This textbook, like most AP World History textbooks also have online resources that summarize the main points of each chapter. These online resources may be the best place to look if you want to refer to a "textbook." Good luck to you.