Your door latch assemblies "should" be cad plated, or dull zinc. I would not recommend replating them as the heat and chemicals of the plating process makes the springs brittle and so far I've not figured a way to put the springs back in place (getting them off is no problem). There's also the rubber bumpers to consider. Nobody want's to reproduce them. Maybe the Eastwood "cold zinc process" might work.
The striker is cad or dull zinc as are the shims. Those are easy to replate.
Jim