This was a suggestion I made when I did the conversion almost 2 years ago. I wasnt so much an issue with the stock grill as the horse and the 2 fogs made a good cover. It becam a bit more noticable with the center fog grill but with the GT500 grill and losing the 2 fogs, I knew it was going to look bad so I masked off radiator and went to town with black rustoleum. Use good quality paint and do a couple of coats an let cure properly because you dont want it chipping or peeling later.



Notice the painted radiator supports

 

I also removed the horns later because they show against the radiator, or you can paint the silver to sit against the radiator better.

 

Rattle can paint. Tape and newspaper everything.
Overspray is a biatch and it can be prevented.
No need to remove the bumper cover or anything like that.
It must be pristeen clean.
Mine had less than 100 'never seen rain' miles when I did it.
The metal was not dirty one bit and I scuffed it up
with a scotch brite pad before painting.
A little brake cleaner on a rag will remove any
oil or waxy substances before painting. Primer is not required.