Frame Dimensions - Is this a surprise?

[65GMCFirstride]

My son and I are restoring a 65 GMC Truck. I noticed the front bumper bolts were about an inch from their original holes when we bought it. Everything else seemed straight (door gaps, bed and cab alignment, etc.). It drives great...straight down the road. We have it apart now and you can visually see the front frame rails are pushed to the passenger side a bit. So, I decided to measure it. The measurements show the front frame rails are out the most, but all dimensions are off a bit. I am taking to the frame specialist soon to let them do a more scientific analysis, but I am interesting in knowing "Is it common that the dimensions are .25 to.5" off on a 46 year old truck or is my frame Whacked?" Thanks!