What bushings are needed for a 68 Chevy grille on a 71 GMC

[CarlsLQ9SS]

I put a 68 grille on my 71 GMC fenders and mounted my headlights directly to my 71 radiator support. I like the look of the 68 Chevy grille better than the gmc. The question I have is do I need to use 68 Chevy radiator support bushings or can I use the 71 gmc bushings. My son tried to mount mount my number and the bumper wants to rest on top of the lower part of the Chevy grille. Any advice is greatly appreciated!