Do you have the car apart? If you strip down the front end- remove all the sheet metal, drivetrain, suspension, etc you could support the remaining car shell on jack stands (support the front part of the car under the rocker panels and use some wood to help disperse the load) and remove the subframe. It's all of 4 bolts at this point. Be sure to untorque the bolts first before jacking the car up in the air. Perhaps soak them with "PB Blaster" or the like for a few days beforehand.. The bare subframe itself is not that heavy. I can pick one up and carry it, and I haven't been to a gym in over 10 years. They are just long, awkward and front heavy, so use a floor jack to support it at the cross member and the back half will be very easy to lower/ lift as needed. Of course, having extra hands always makes the job easier.
While the frame is off you can inspect for cracks, strip the paint and grime off/ have media blasted, etc and repair the crack(s). Some simple measuring could determine if your frame is bent. These can be straightened at a body shop (they may want it still on the car- call a shop first before taking it apart to discuss.) You could also use another first gen (67-69 camaro/ Firebird) or even a nova subframe (68-74) as a replacement. Or, you could opt for a new one. If you want a stock one they are reproduced now, I think Classic Industries sells them (amongst other places) Or go aftermarket. Numerous companies make them. some offer complete assemblies with suspension, steering, etc. Determining your budget, skills, and project goals will help you determine what you can and should do. The cheapest route will be to either use your frame (depending on condition/ repairs needed) or replacing it with a used original. I see them listed for sale on various forums regularly. They are still plentiful and available.
If you wish to see a '67 Firebird be completely torn apart you can check my build threads of my car at either car domain or Hotrodders.com
http://www.cardomain.com/ride/392973...ntiac-firebird
(more detailed with pics and descriptions)
http://www.hotrodders.com/forum/jour...ournalid=20939
I hope this helps. Let me know if you have more questions.
-Brendon