Contact the public school and arrange to have him shadow for a day.
In arranging to have him shadow for a day, mention his 2e, what supports have helped him so far, and that he would need an IEP/504.
Be sure the public school understands that he has fit in well and excelled in his Montessori learning environment, and you are looking for a successful transition to the larger, more highly populated school.
Being proactive on these measures may decrease the likelihood of poor behavior in the new learning environment.
