Overhead Squat 3-3-3-3-3 reps
If you have the necessary shoulder flexibility and want to do a low rep max, then the clean grip is the way to go. It’s a much stronger, stable position. But don’t neglect the snatch grip though. You need that movement specific exercise to get better at it.
In the video Chad Vaughn says that, with a clean grip, he can probably overhead squat 110-120% of what he can overhead squat with a snatch grip.