Take your original frame. Build a steel table. Make the appropriate spacers, towers etc. to hold the stock frame and voila, frame jig, good for Chevy trucks from at least 55-59.
Don't forget to have your stock frame measured and cross-measured before doing the above to make sure it is straight and square with no racking, no twisting, no bows and no bends.
Thanks for that.
Small problem; the existing frame has a Camero front clip already attached, and not very well. I really don't trust it. I was hoping I could find some drawings to save some time and effort.