I made a special gouge to ease the trimming of the bushings, by cutting and grinding an edge to an old file. The back of this gouge has a slightly curved surface, much like a so-called "in-cannel" gouge.
I did a very light reaming of each hole before glueing two maple shavings on each hole. After the needed thickness was reached, I glue-sized and scraped the shavings flush with the pegbox walls. Then I did the varnish retouching and a very light French polishing. The retouch adds a slight halo around the peg holes, which simulates the dirt accumulation and helps to hide the repair. In the pictures (taken with my phone) the varnish retouch looks more opaque than it really is.
Finally, the old pegs have been thinned down on the peg shaper and reinstalled.
