According to Wells Gardner's website: CGA-SVGA, 15 kHz-38kHz, so no XGA (1024x768) support.
Arcade monitors capable of XGA are very rare beasts. I only know of one that also supports all the way down to CGA timings, and that's the Billabs multisync (made by Wei-Ya), and I'm not sure it's available anymore. There are some specialty "high resolution" monitors floating around that do VGA - XGA, and some can even go up to SXGA (1280x1024), but these won't usually do CGA or EGA timings.