The FORD shop manual gives lower body measurements however I have never found any upper body measurements. The important thing is the structure is square. I would install your very front and back fender bolts and do a X measurement and that will tell you if your upper body is square. A tram measuring bar is the tool for this but a simple tape measure will work as long as there is no obstructions in the way. Another good tool to check the shock tower placement is correct is a one piece export brace, if it fits in the holes OK you know your shock towers are in place. If your car measures out good I would then install the hood and fenders to check fit. Remember to fit everyting first before you weld and it will save you a lot of grief later.