You will have better left hooks. Like Miguel Cotto does. But dont be sad about your right straights. You can learn straights all the time unlike hooks of the lead hand or the jabbing arm, because you need to combine your body weight and the natural strength of your arm to have a great left hook. And we could say southpaws have their strength at the left. And also remember that the legs are important when hooking. You need to pivot the outside foot. Thats it and you can have the perfect KO punch. A left hook from a southpaw!