I advise the former. Have your 3D game object instantiate its own UI info element, and parent it to the appropriate "HUD Root" object. That's what I did in Windward. All ships create their own HUD element, and since they are the ones that create it, they get to keep a reference to it. When a ship gets destroyed, it also destroys the HUD element. When the health needs to be updated, the reference is present so there is no need to go searching for it.
