I’m a special ed teacher here in VT and we use the Stern Center for students with more complex reading disabilities. They do an amazing job and will give you a more accurate and precise evaluation and diagnosis than most public schools. Their evals are also very expensive but also worth it.
Expect a lengthy evaluation report with detailed cognitive and academic scores. They also offer excellent suggestions for accommodations and tools to help a student who is struggling with reading. I find their evals to be invaluable when working with students and writing their IEPs.