I dont question sellers prices anymore. Its your car you can ask what you want for it. If its too high, and it needs to be sold the seller can adjust.
Very seldom do you see a Shelby under $50k. A 4speed, AC car is on the top of desirability list for most collectors and its a good color.
It appears the correct number is 205177. I would look at the totality of all numbers and there is no question its a matching numbers car, even with the stamping error.
I am more amazed at the note on the build sheet “METRIC SPEEDO”. I wonder if the car had it or it was swapped out by a dealer? I guess there wouldnt be a need for it once the car showed up in Illinois.