Even using Express transportation, you'll really be pushing it. I'd put your chances of making it at less than 50%
If you rush (and I do mean rush) through dinner, you may be able to make the 5:50 express transportation pickup. That would put you at AK a bit after 6:00. The chances of getting a fastpass is slim to none. You may be able to do stand by, but I wouldn't count on it.