The Levi's shirt as previously mentioned is worn the majority of season 8, the red tab on the pocket has been removed and the whole thing has been lightened and distressed. https://uploads.tapatalk-cdn.com/20171217/2f5d63407514da91ede427afe1ed2357.jpg
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That shirt is definitely a Levi's Barstow shirt, but it's most definitely not black. I'd say the original is light blue and has received a dye job to darken/blacken it. If you look closely at several pictures you can see that the color of the stitch thread is light blue, and overall the shirt seems to have a washed out grey/black color with blueish undertone.
As for the black pearl snap button caps, you can easily order them online and replace the standard Levi's button caps with the black ones. You don't even need to change the studs as they should snap perfectly into the black button caps.