Dr_Pain said:
I didn't fully type out how to do it, but I was thinking if you drilled out the welds where the cut up pieces are and replace them with the pieces out of the donor by welding them up at the same spot welds, why would it be any less structurally sound? Properly welded, the piece in the roof wouldn't be any weaker than a full piece. Now, that being said, if you thought I meant to cut out the same piece from another car and butt weld it in, then yes, that would be bad, but it can be done properly and be just as good as the original.