Update. I was worried about the inserts staying put, but this past weekend the front sight had no issues moving around (I didn't have the rear at the time).
Bubba finished up the rear and made the holes a little too big so the inserts floated around a bit. I tried tapping them into the sight so they would grab, the that only minorly worked. Then I just turned the thing upside down and torched the thin ends with a lighter. They curled up and look horrible, but they 'sealed' into the sights now and still gather plenty of light. I'm gonna try a fresh pair tonight using a soldering iron to heat the sights directly and set the inserts.