Definitely take the free online SSAT test.
Another school to consider: The Asheville School in North Carolina.
Why do you want to attend boarding school ?
What do you think boarding school life is like ?
P.S. My suggestions at this point are:
The Culver Academies in Indiana (I suspect that this may be a great match for you.)
St. Andrews School in Delaware
Mercersburg Academy in Pennsylvania
Indian Springs School in Alabama
NMH Northfield Mount Herman School in Massachusetts.
Also, it is common for students to start boarding school in the 10th grade even though most of the class started in the 9th grade.
Students attend boarding school for a variety of reasons. Common reasons are:
Need more challenging academics;
Commute to local private school is almost one hour each way;
Parents are working overseas;