We suspect DD (ok, just at the preschool level, though) has sensory issues (as did her pediatrician before we moved) but haven't gotten her formally tested since our insurance doesn't kick in until next month. We knew we were going to send her to a private school here since publics are just not safe where we live (outside of the US) but we really thought long and hard about what situation would be best for her. The worst environment possible for her is filled with loud noises, lots of kids, and chaos. We had a school recommended to us that was play-based but knowing DD that would've led to her acting out. Instead we found a very small private Montessori school and she loves it. The ratio between teachers and students at her level is 3 to 1 and all the sensory materials there are like heaven to her.
It's really be tailored to her needs. She's advanced in some areas but her fine motor skills are not stellar so she has the opportunity to work on them. She also gets the direct attention that she needs (and craves) while being able to move when she needs it. The teachers have also been great on picking up on DD's moods and if she starts getting nervous/looking like her mood is about to implode they take her outside and give her the running around time that she needs.
I'm not sure what your son is like, what activities work best for him or what schools you have available but could you possibly talk to your OT and see what type of activities he needs and then think about what type of schools could provide that for him?