In Orange County, new high schools are usually built (there are a few exceptions), to cater to an enrollment of approximately 3,000. So, in that sense, at capacity, all but one public high school I can think of, would meet 8A classification. Several Orange County high schools currently have enrollments in excess of 3,000 meaning they exceed capacity.
I am not sure what the deal is in Seminole, but all high schools there are currently in either 8A or 7A for football meaning their enrollments vary from about 1,900 up to well over 3,000.