Rear quarter body help needed

Flanging makes for a stronger and easier to weld seam for sure, but it sure makes an ugly seam to dress up on the inside. It can't be done on every car, but on this one I would have trimmed the replacement panel on the bodyline and slid it inside. The inside seam would have been right at the bodyline so a finger wipe of plastic or a really tight wipe of seam sealer would make it nearly invisible.