project "bastard case" !

I just refinished the grille on my 71 ..

I disassembled it, washed it, and used wet/dry 500 grit paper on the flat areas.. (water bucket with a little squeeze of dishsoap in it to help get rid of any grime on the plastic)
then used a red scotchbrite pad, with water, to scrub and scuff all the areas in between the slats and in the corners..
Then, once it was all cleaned off, and dry - polished (by hand) the clear lenses using Meguiars plastic cleaner and polish.. then taped off the lenses only with blue masking tape.

Sprayed the silver areas (border of the grille, lens areas, and the 'stripe' that goes around the inner part of the grille.

Once the silver was dry (about 45 min), I taped off the areas that I wanted to stay silver (the strip around the inner part of the grille, as well as the border of the grille, and the lens areas), using blue low-tack masking tape and professional grade 3M fine-line tape for sharp, crisp edges... then, sprayed the semi-gloss black on .. used a full can to ensure coverage in between all the slats and corners.. let it dry, then pulled off my tape, exposing the silver areas.. looked great, took a total of about 3.5 hours including prep time. A lot easier to do it this way than spraying the black, and then taping it to spray the silver.