First, I need to say that I'm not an expert, but I do have a sort of hard hat collection. I have about a dozen different hard hats, just because I like them. One of these days I'll get around to posting pics. Anyway...
I took a quick look at my collection and of the different manufacturers represented, none adjust to any size bigger than 8. MSA products seem only to go up to 7 5/8. The others all seem to go up to 8--that includes Bullard, Wilson, Norton, and Tuf-E. (Personally, I like the Bullards the best.) Of those, only one has any adjustment for depth--that one is the Norton.
None of these hats are new, so I can't even say for sure whether all the manufacturers ares still in business. I looked online for Norton, and found a lot of computer software, but that obviously won't keep you from geeting a fractured skull. What I did find was North Saftey Products.
This one looks pretty similar to the Norton one I have and the description says in part, "Pin lock adjustment, 6-point nylon suspension with 3-level height adjustment."
Whether that will help you, I don't know.