If you mean large as in half kilo large, try a 9/0 or 10/0 through the shoulder. with 80lb trace of about 2metres. Weightless as a mullet that large can swim for its own. Cast up current and let it drift.
Smaller mullet can be anchored down with sinkers if the current is too strong. traces of a metre or so if they are on the bottom. Pick the size of the hook. Make sure you get the finest gauge you can use as a huge hook can kill the mullet really fast. For the smaller mullet a 4/0 or 5/0 would do the job fine for flathead, school jew, trevally etc
Matt