Hello James, my name is Jesse with Hyson Music.
Unfortunately, needing to justify the value of music education to administrators is all too common. I would suggest Googling the subject matter. There really is a TON of useful content online that can be of use to you.
Also, the following website can be a great resource as well: http://www.childrensmusicworkshop.com (I have no affiliation with this site, I am simply a visitor).
With that said, a little poking around and I am confident you will find the information you are looking for. Best of luck!