It might be possible, I did this with a gauntlet legends board which had a voodoo graphics card and it worked fine.  I think the video signal is routed back thru the pcb just so it can go out the jamma pinout.  
You also have the fact that your board is outputting a med res signal so you have to have a monitor that will support that.  Or does gt fore have a dip switch setting to change to vga?