Looks great! Very nicely done repair and it will be helpful to a lot of people down the road.
From what I have read here it often isn't the LEDs that burn out, its the traces on the circuit board that go bad. That is why they go out in stripe patterns most of the time.
Also maybe this can help someone too incase they goof like I did.... I cut high on one taillight, and like you said you could see the cut because the inside of the taillight is all reflective finish. To fix it I put a little bit of aluminum tape over the cut on the inside; its not noticeable now unless you are really looking for it.
96 Cougar Sport
96 Tbird LX