The original 67 A-body front and rear window trim were plastic based extrusions. Over time it shrank up leaving unsightly gaps at the corners and it also lost it's luster. Not to mention the stainless steel corners and straight joint covers were not securely held and would just disappear. More ugliness. Last time I looked, a set of 4 re-pop corners were going for around $50.
It is very common to convert 67's to 68-69 stainless trim. There was a good reason Mopar abandoned the 67 design. Do yourself a favor and go that route.