IMO, the most telling of all measurements is to measure the X of the frame from a point in front, to another point in the rear, long as they are the same points on both sides....that measure has to be identical, obviously, so the points chosen have to be identical to both sides....
best done on a 4 post lift, or with body/frame separated....tough to do with all that together, or engine in place....
I typically choose a front suspension point, say front of lower t-arm mount, then go diagonal to a rear point....
at least you know the thing will track right, then...