I have not done a 67 skylark but the trunk drops are similar to all the cars that you mentioned. The most similar, if memory serves me correctly is the Cutlass. I'm sure with a little trimming (you usually need to trim any part like this regardless, even if it's car specific), it can be made to fit and fit well. I have done several 66, 67 Chevelles with this same problem before aftermarket parts where available and made the piece. If your originals are good enough to use as a pattern, that may be another option.
Hope this helps.