69 Barracuda grille work

I like the argent grille better, that looks more correct. My dad has an A56 cuda that has the argent silver grilles and that looks more to the late 60s

The standard 69 Barracuda grilles were argent.
The Formula S grilles were black and so were the 'cuda models (A56, A57, A13) The factory description of the 'cuda models clearly states that fact.
However, if the factory happened to be out of black grilles on that particular day, I wouldn't put it past them to use argent grilles just to keep the line moving. My 69 A56 car had argent grilles on it in 1979 so it could have happened. Every original black grille I've seen were molded in black plastic but who knows, maybe they did paint some argent ones black.

ALL of the plastic ring headlight surrounds were argent on 69 Barracudas.

The deck lid panels were argent on standard Barracudas and the 'cudas. Formula S cars were black with the "S" medallion.

As previously mentioned, the radiator supports were crudely blacked out by the factory except on dark colored cars so the body color didn't show through the grille(s) from the front. They apparently did this from a pit in front of the car and sprayed upwards. Coverage was entirely dependent on who happened to be doing it that day on that particular car. Not only that, but it looks like they were painted with the headlight wire loom in place along the top.

Cars with polished grille surrounds (67-68) and completely polished aluminum deck panels (68-69) are incorrect but owners do whatever they want over the years which only adds to the confusion.

The O/P is converting a /6 car so he's doing what looks best to him, so be it.