Joel,
I just saw your post so I apologize for not responding earlier. What is your intended use of the car? Expected power level?
Our g-Bar and g-Link systems are designed to bolt into the car using stock suspension mounting points to properly locate the system. Once it's bolted in place, there is only minor welding required to properly secure the system to the car. For your 73, we also offer the option of a new set of frame rails. They are custom bent to fit underneath the floor, allow more tire clearance, add a tremendous amount of strength and rigidity, and work with the stock fuel tank.
There is a lot of information about the g-Bar systems
HERE and
HERE and more info about all the options available for the second-gen Camaro/Firebird
HERE.
Don't hesitate to call me, my extension is 247.