I wasn't convinced that replacement lock barrels and the fiddly mechanism were ever going to be reliable enough so I opted for central locking. I have to admit that when I unpacked the kit I was hit with a wave of anxiety but I've taken my time and watched some YouTube stuff and had a go today. The most important thing I learnt was that you don't connect the servo directly to the lock mechanism, it connects to the existing rods with a clever little clamp. After Much thought I decided to mount the servo just above the lock handle, plenty of space and easy access to the rods. Two simple bolts and the locking clamp straight onto the locking rod. Really amazed how simple it was and it worked first time. A few tips, fit your new rod to your servo before bolting it in place otherwise it's a bit difficult to get in. Make sure your electric windows are open so you can reach inside if you accidentally lock yourself out!
Btw I have a secret override security system for getting in the car in the event of an emergency, but I can't tell you about it!