Locks and even retainers are so cheap it does not make sense to reuse them...especially the locks. If the springs are stock diameter, you can reuse the stock retainers. The locks only cost a couple of dollars and should not be reused.
Hope this helps,
Advanced Automotive Machine
I would never reuse the old retainers and lock unless you want to replace a whole motor because it dropped a valve after stripping the locks through the valve. Seen more times than I care to remember. Beside's it is cheap insurance.