On our 72 SS, the trim IS there, but I'm not sure if it was part of the SS pkg. or the Custom Ext. pkg. as indicated on the build sheet-ZJ2,. Hope this helps you some. I'm sure there are others here who can give you the real answer.
I've stripped 3 novas for parts and all of them had the bright trim. None of them were SS cars. My 72 SS came as a stripped shell so all the trim had been removed before I got it. I know none of this really answers the question, but I don't think the bright trim was an SS option. It might have been another option that was automatically added incase the SS option was chosen!
My dad's '70 SS has them. We bought the car in 1985 and it had its original paint and vinyl top. I would think that if the car has a vinyl top, then there would be a good chance it has the chrome moldings.