Modernly left handed flintlocks have left handed locks and sideplates and stocks. Traditionally, if you were a southpaw, the stock would be set up for you but the lock was righthanded. The exception is if you were rich enough for a gunsmith to make you a lock and there were some left handed guns made in the days of the olde.
BTW, I took my first class on how to make a flintlock because I couldn't find anyone to make a southpaw one for me. Now I have a couple.
