Is the grille on a 1968 lemans interchangeable with a 1968 gto?

fix it the right way...KEEP UP THE VALUE....they make after market kits to up date them......................

Yes, you could swap the front bumper/grill parts but the car would be better to preserve as a valid GTO body. Parts are available to get the hidden lights to work right and you would have a better value car when the work is done. What are the lights doing that you want corrected? I'm guessing it is the doors that cover them.