[MP&C]

That "correctly" is a severely loaded term. One would have to see the panel first hand to weigh all the options. In many cases you'll find rust issues above a drip rail or above the windshield that stem from condensation gathering on the inside of the panel. If there were any such indicators at all, one might lean more toward a new roof skin, kill two (or three) birds with that one stone. If the steel headliner could be removed or even pulled down on three sides by drilling out spot welds, that may be another option for less expense in replacement sheet metal. Based on someone's lack of a welder, or perhaps metalworking skills, or ??? it may be the best option to use adhesives. Again, each circumstance would be different. If a truck was on bags and going to be slammed on the ground then one may be more concerned with a ghost line on the roof skin and pick a different option than if it's a lifted 4wd where any ghost line is far from being seen.