Boropark and williamsburgh are chasidish. Flatbush, and Marine park in brooklyn are a mix.Kew garden hills in queens and flushing are a mix as well but does not have as many education or employment choices as brooklyn.
Far rockaway is very nice as well but your monthly expenses will be very high for all said purposes it is dependent heavily on the five towns for its shopping work and educational needs and cars are a must. As mentioned above the Boys Yeshiva in that area Darchei Torah is an excellent yeshiva and as referenced by the above poster for a child with needs they do a tremendous job of integrating kids.Yeshiva tuition and day camp will run you about 30% more then Brooklyn. As you said you were from L.A. the five towns are very similar in cost.
Solely on your brief description of your son, I can think of a few Yeshivas in Brooklyn that can cater to your son very well in mainstream classes. Therapists meet with boys during and after school hours and if your son can be only partially mainstreamed there are boys yeshivas that have classrooms within the class or use arrow smith and other resources if necessary.
I actually know of a few boys with sensory issues and adhd that are doing quite well.
If your son needs a Yeshiva with modified learning but not necessarily full special ed there are a few of them in Brooklyn.