I have replaced almost all the emblems on my 'bird, the only ones I have had any problems with are the "Pontiac" trunk letters. I had to waller out a few of the holes that hold the letters in place. The "I" was so bad, so was the "T". Very pleased with the rest.
Another issue is on the 'bird emblems is the red cannot be duplicated. You can use model paint, but will not have the mettalic appearance of the originals. If someone on the board knows how to do this great, but nothing looks as good as the 'bird emblems in their original appearance.