[projectfolly]

In my opinion, I'd declone it. I'm a little biased since I remember well when my dad brought home a brand new liberty blue Custom S! Don't see many around these days.
There weren't many Custom S(s) making more rare than a GTO.
You have a conflict of statements with the GTO equipment against the '69 (Tempest, LeMans) Custom S quarter marker lights. No cutting required.
You have accumulated the parts.
Besides, you can always put the GTO parts back on it if you choose!