Theres an SAT august 24. If he’s interested he could do a little studying now and take it in a few weeks. 790 is certainly not a bad score. However, many students get 800s on the Math 2 because there is a large curve. He’s only a question or 2 away from an 800 so its definitely possible. I would recommend retaking the rest sooner rather than later because the information seems to be fresh in his mind.