Most of them I have seen has a texture to them, but it is a soft feel, like velvet. maybe? I have seen some smooth black ,but I do not know if that is correct.
I agree. I just went out and had a good look at mine (a 62,000 mile car).
It is a fine texture that only camouflages the natural wood-grain but does not fully hide it.
For someone restoring one of these my best guess would be to find a light textured paint and use a dry spray stacking process (hold the spray can high allowing multiple thin coats to fall on the panel) until about 80% of the wood-grain becomes difficult to see.
Next, go over the panel with a satin black until you have an even color.
One question would be: Were these finished by a person or a machine in the manufacturing process?
If they were finished be a person, what is "correct" could be all over the place.
Did the person on the line texture the panel for 30 seconds while talking to his buddy?
Did he fart and giggle, Spraying more texture on the left side than the right?
Did he spend 1 minute spraying product because he was mad at his boss and wanted to "Show the company" by wasting product?