Mills site says that they are for hardtops and they do not fit convertibles. https://www.millsupply.com/auto-bod...-buick-skylark-rear-quarter-panel-686850l.php
Hence why I have cut back on posting. Need several other people to endorse what has already stated...
As others have said you can use the repro hardtop skins as patch panels. If you look closely at the hardtop panels the roof line starts about mid way on top, and the convert is flat. These are just outer skins and not like the originals.