There's no publicly available, definitive ranking of New England boarding schools by average SAT scores. Schools don't always release this data consistently or in a comparable format. Also, the average SAT score can be misleading, as it doesn't reflect the full range of student abilities or account for factors like self-selection bias (students applying to schools with higher average scores tend to have higher scores themselves).
While some publications attempt rankings, they often rely on self-reported data and use different methodologies, making direct comparisons difficult. To find information on specific schools, you would need to consult each school's individual profile or website. Even then, they may not always publish average SAT scores.