Frame Conectors instructions
you can get the frame spec sheet off Ebay I bought one and it covers alot of A-body year models.
if I can find mine I will try and post a pic of it.
if you have a welder and basic grinder with a cutoff wheel and some other hand tools you can make what you have work.
put the car on jack stands. put it only under frame sections not moving suspension.
using the door sil as a place to put a level front to back and see what you have.
then take a long piece of material that is straight lay it from door to door sil, you mave have to take the seats out and make sure you go over the trans tunnel and see if level side to side. that will tell you if the car is twisted.
from the looks of the frame damage it looks like it was hit in the rear.