My Dad did the frontend 10 or more years back. He also used a Camaro in these years. I think his was a 1976.
My truck will be a GMC eventually, I don't know if it is going to have a Chevy grille until I find the GMC grille or not yet. My truck is an original Fleet option truck so either way it will never be original again. My Dad and I have both given away the original parts thinking they were wrong. Then I found this
http://www.oldgmctrucks.com/page0287.html DOH!!! To late to go back now, could never find those parts again. But the answer to your question is, I will eventually have 100% GMC gear. I just have to find it first. Thanks for your interest guys!