Body Shell Inspection

[69-er]

Tomorrow, I will be looking at a 69 for a possible purchase.  The rear of the car, (quarters, wheel housings, rear panel, deck filler panel, and full trunk floor) was removed.  The front of the frame rails were left attached to the body.  The panels are now installed and the rear of the body is now complete.

What would be some quick and simple checks to insure the body dimensions are still within specs?  I would imagine with all of those pieces removed, there would have been a possibility of twisting, out of square issues, etc.  It's a roller at the moment.

I thought of using a plumb to check for squareness.  I know what the datum line measurements are but I'm not sure how to use them to detect twisting.

Thanks for any tips you can offer!

Larry