I have similar issues with the rear channel, which had a driver quality repair years ago. I sort of postponed a proper major repair and vinyl roof removal by running a bead of butyl below the chrome. I saw pictures of yours at the beginning of the thread, you may be slightly worse off than me though. If your car was mainly out of the weather hopefully the trunk may not have fared too bad. Although driven daily, mine was garaged, and was rusty where the water would have pooled, above the sub-frame area.
On an unrelated note, did you see what I would call the "gasser style" 1967 500 in this thread?
4th Annual C Body Show - August 1st
It may be a members car or have been discussed previously here.
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