Yes, you can do that, but it would obviously be easier and better if you started with a '70-'73 Firebird. The rear would take some metal work. The front is fairly "easy"(bolt-on), just a new hood, fenders, nose, and valance and the matching headlight, signals, brackets, etc.
I think some people might cringe that you changed a Camaro over to Trans Am clone though. There are people that have already done conversions on '70 to '73 Firebirds to Trans Am clones and it might actually be easier, cheaper, and more visually accurate to buy a converted or partially converted car. In your case especially, the conversion cost may be more than the cost to just buy a '70 to '73 Firebird that's already been TA cloned or partially cloned.
Whatever you decide, I wish you good luck! I share your interest in the '70 to '73 Trans Ams. I owned a '73 TA and wish I still had it!
