That's something even the lawyers involved with the intellectual property (IP) of officially sanctioned emulation (i.e. Wii Virtual Console) might not know.
ONE THING IS CLEAR: You cannot assume that the original rights-holder actually has possession. In the history of any company that has evolved/gone bankrupt/disappeared over the past few decades, you will discover that the IP has changed hands or (even worse) has entered "limbo" ....
'TIS A DAMN SHAME, of course.
Folks have proposed buying firesale IP so it can be loosed upon the world (for all to enjoy freely)... I would gladly contribute $$$ for such causes...
BOTTOM LINE: I HAVE NO ANSWER FOR YOU.