why don't you just restore the firebird and drop in a chevy drivetrain. i'm a camaro fan, but the firebirds are still a very nice car.
like clill said, you might give it a body lift, but it will always be a firebird and like steve said, it may be cheaper just to go buy a camaro. body panels aren't cheap, and if i'm thinking correctly, you would need almost every panel except for the body shell and maybe the doors. and then to have a body shop do the work, big bucks.
buy the firebird, restore it with a chevy drivetrain and you'll be just as happy.