M.B.
Does he have an IEP?
If you are having ARD meetings for him, you can also address your concerns with that.
Talk to the teacher ahead of time... if he is a sensory seeker, find acceptable ways for him to fidget... playing with a fidget, using a weighted vest/lap pad, quietly tapping his toe or tapping his hand on his leg.... these will all possibly help him focus without disturbing others. Does he have oral sensory needs? If so, an acceptable "chewie tube" or "chewie necklace" may help with that.
Be sure he gets into a classroom where the teacher DOES understand his sensory needs... some teachers are old-fashioned and want the child to sit still and listen... very difficult for some of the SPD sensory seekers.
Talk to the teacher about allowing him "sensory" breaks.... the chance to get up and move around the room at acceptable times. Maybe you, the teacher, and your son need to work on some signals for him to give her so she understands he needs a break?