Following is a compromise joint. Rail sizes change and special joint bars were used to compensate for the difference in rail height and width. I had a new crossover installed on the KJR and the contractor had folks that did not know there were rights, Lefts, and inner and outer bars. Ihey had the bars reversed so the rail heads were aligned on the outside. They were going to build the rail up with weld on the inside to match. I told the job forman it would be much better to put them in the right place. 
They switched them around and that did the job, They had never done anything that needed comp bars so it was a learning experience for them too. Unfortunately I don't have a photo to show the top of the rail head.
This next photo shows the same thing done with a thermit weld. Going from 136 PS rail to 132 RE.
The last I have to offer are photos of Koppers Co. Insulated joints. The prototype uses them too.
Last I have a section of mainline taken in 1977 that shows the difference in the color of the side. I have noticed the newer rail tends to appear more of a gray/blue than the older.
Charlie
They switched them around and that did the job, They had never done anything that needed comp bars so it was a learning experience for them too. Unfortunately I don't have a photo to show the top of the rail head.
The last I have to offer are photos of Koppers Co. Insulated joints. The prototype uses them too.
Charlie