What kind of effect are you looking for? Statically sized text above an object that cannot be occluded, or text that appears to be physically above the object and translates with it?
If you're trying to do the latter, the way I would go about this is instead of using blitting, texture a 2d rectangle with bill boarding enabled, and attach it as a child to the object it should be above, then translate it up some number of units until it is above the object.
If you are looking for statically sized text using blittting, this could take some thought.