Remember you have upper body dimensions also. The Frame can be square and the upper body not square. That would include the A-pillar. (hinge pillar) It is not uncommon for an A-pillar to move rearward in a collision.
You really need some frame dimensions. Unless you can establish a center-line You will need a width measurement data and correct length and then cross-measure. If everything is level, you can get fairly close height measurement from the floor. Like other people have said. If the sheetmetal fits and it will wheels align you got it made. Buckles can influence structural integrity. Yours doesnt look that bad.