I've seen the grilles painted black before on a orange car. I didn't care for it.
I saw some painted body color ( white ) too. That made the surround look like an extension of the header panel turned back into there with a small outer trim applied. Didn't look bad at all.
I guess you know bolting the grilles back in while the header panel is on the car is a chore. Its easier with the header panel face down on the ground but removing it requires removing the front bumper, etc.. I've done it both ways.
If you do remove the header panel be sure to loosen and spread the front of the fenders a little. Otherwise the bolt ears on the header panel will scratch them. And lower the hood to check/adjust that gap across the front before tightening the bolts. Either way, have fun :)
