What's the correct finish on these tabs?

Depends on the year. My 66’ has paint only. My 72’ has the rubber type coating that is painted over body color.
Paint over the rubber seems to be the way it was done in these years. I wonder how the pro resto guys address this? If you paint them and then bend them around the wires, the paint will crack but if you bend the tabs before painting it is difficult to paint both sides of the tab. And of course it is also hard to fish the wires through then.