['68OrangeSunshine]

That's a superb list that Dillon Rock uncovered. Too bad for my interests, that it stops in '66, since all my trucks and projects are '67/'72. But as Wm. Shakespeare says: "There are more things in Heaven and Earth, Horatio, than are dreampt of in your Philosophy..."
I once had a theory, that the 292 originally debuted in Alpine Green, because its predecessor the 261 was Alpine Green and that was to differentiate it [at-a-glance] from the blue 235, that was otherwise identical on the outside. Now I realize I was never that smart to know how all that stuff went down 'back in the day.'
A guy in the 67-72 forum has a '70 or '72 350 that he's sure was originally painted Lo-Gloss Black. It has the right provenance. I've been pontificating the line that "No ALL engines after 1967 were Chevy Engine Orange."
So here's my 'New Theory': Perhaps, one Friday afternoon, after a few pitchers at lunch, the paint guys ran out of Chevy Engine Orange and sprayed the engine with the same Low Gloss Black they used on frames. The production line would not stop while somebody found the ''correct'' shade of Orange, it had to keep running along, regardless.
I'm not infallible, I wasn't there. How could I know? Also the Marketing Guys may have some showroom eye candy thing going on, by switching up the engine colors.
At this point, we'll never really know, but it's fun to speculate.