This kind of shit. It's exactly what infuriates MAME developers, and why these kinds of threads are bullshit.
There are two different situations here.
One is that the printed documentation on the boards happens to claim that one background color is correct.
Meanwhile, there's evidence based on analyzing the individual PCBs that many of them had another color.
You people piss and moan as if it's us MAME devs who are ultimately responsible for you not having the luxury of playing the game like how you remember.
That's great that you're so passionate about Gorf, but if you really care that much, go track down some original developers and talk to them or track down some original hardware engineers and talk to them, and then get back to us with a clear-cut answer as to what the "intended" background color was meant to be. Because the current evidence is entirely unclear, and you people are bitching at us over something that we didn't control at the time, because we don't own a fucking DeLorean. At the end of the day, no matter which color we choose to be "correct", people will piss and moan about it.