I'm not sure if this information is needed, but if added it should be discrete and out of the way. Star Citizen displays the galactic plane in the radar globe, Evochron Mercenary show an artificial horizon (attitude indicator) on the HUD, and IMHO both of these only add visual clutter for something that is only useful on specific occasions. I don't think the ship hologram would be a good place either, there is some crucial combat info around it need to stay as easily readable as possible.
A good place may be the compass: the dotted cross could become some sort of attitude indicator. Not very precise, but it would give you a rough sense of your orientation relative to the galaxy.
A good place may be the compass: the dotted cross could become some sort of attitude indicator. Not very precise, but it would give you a rough sense of your orientation relative to the galaxy.