I believe the 47 pull down type handles will make it difficult to retro fit a keyed lock onto the drivers side. If you have the pushbottom type handles you could replace the non-keyed cylinder with a keyed cylinder from another passenger side handle or a new lock from the catalog.
You may also consider replacing the locks with bear claw type latches but your drivers door locking from the outside still would not be solved.
You are probably aware of it but if you push your inside door handle forward, it activates the door lock.