Just got another project.....but not an A-body

The profile is actually pretty good. This side was too damaged to do a comparison. I just went out and fit the pass side up. The shape is great. Nice and even all the way around. But I was able to push it right up against the body inside the original. To me this would say the opening is roughly 1/8" to 1/4" smaller than stock. It could just be that coming in from the bottom allowed this due to it's shape though.

Edit: When I installed the driver's side, I used measurements from the door and the top body line. I know the wheels sit much closer to the front of the opening so that was the distance I considered to be the most important.