There's not a ton of reason to try to dump low res into an LCD unless you need compatibility with an actual arcade boardset. The LCD will just upscale it to whatever's native, anyway, and it'll usually do a pretty poor job of it. Far better to scale in software using whatever means you find best (you can also do scanline effects and similar, if that's your thing) and sling native res at the LCD monitor. Modern video cards are VERY good at scaling things, so it's essentially free with the proper software/driver support.