I'm really stuck on trying to figure out why this happened in the first place.
Easy, it's all in how the Sanyo is wired and the way the signal is being output by the board.
Hook up your 60-1, but switch the dip that will flip the image. Should work just fine. The ArcadeSD unfortunately doesn't allow that.
In a Dynamo JAMMA cab, it wouldn't be a problem, you'd just physically rotate the monitor (they're designed for that). A DK, not so much