The best advice I have is to take your time. Ask yourself why they built something as they did (i.e. number, size of bolts, how stuff fits together, etc.) Take the time to check for wear and damage. Then really ask yourself if you will reuse the part. For example, we are doing an RS grille conversion/core support on a friend's 69 Camaro. He wanted to reinstall the crusty, decrepid radiator overflow tank onto a shiny new core support. I mean this thing looks like it came out of a swamp. We had to convince him to replace it.