I will apolgise if this has been shared before on here and is old news, but a forum member here-Jez Firth AKA Gonk droid- spoke to the original painter of the ANH helmet. He said they used a Rolls Royce black. He couldn't remember the exact code but the go to RR black at the time was Mason's black. A friend got some mixed up but was warned by the paint shop that it was a very awkward and slow drying paint, we tried it anyway ( at this point we were under the mistaken belief the ANH helmet had been brush painted, it was only in a conversation a while afterwards Jez confirmed that the painter had actually mentioned spraying it! ), the really interesting thing was that it did indeed take a very long time to paint, but it starts off a very high gloss and as it drys it tends to turn more of a satin/ matt finish. It also retains a degree of tackiness which means any dust will easily settle onto the surface and if you handle it it's a right bitch for fingerprints.
What was interesting to see was when painting a second coating over it the paint under the surface hadn't properly dried and what you end up with is gunked paint dragging underneath the brush strokes, some the build up looked almost identical to the roughness on the faceplate- including that much debated scar!
The closest match I have found off the shelf isn't a finishing paint as such, it was a can of Halford's guide spray!
The other thing that stood out about Masons black was the original paint code- 501!