Looks like a good deal and I am tempted to go for it! However, I am a bit worried about the arm length, would you mind measure armpit to cuff please? Also, was this bought as a used garment, hence is there any wear or tear noticeable?
If you rather hit the gym than doing yoga, classic deadlifts would be your best bet for a better posture overall. However, I would recommend a full-body workout 2-3 times a week for even better results.