AFP sharepoint - change permissions recursively

hello,
i have an AFP sharepoint with thousands of recursive folders / files.
the sharepoint used to be quite complicated permissions-wise, but I want to change the entire sharepoint to read / write for all users in the OD group "staff".
on a single user machine, i would use sudo chmod -R 775 /sharepoint. what would be a similar action to change the entire sharepoint to read / write for all users in "staff"?

i have tried to change the permissions in server admin by adding an ACL for staff for read / write (this folder, child folders, child files, all descendants), but this seems to only change the permission for the root of the sharepoint itself, and not recursively. POSIX has the admin user as read / write, staff as read / write, and others as read-only. when I browse the folders inside, the permissions are the same for POSIX, and no ACLs.

the sharepoint shares over AFP, FTP, and SMB.

thanks for taking the time with a newb question.