Just so this may be of help for anybody looking to upgrade tuners in the future: it is no longer necessary to drill headstocks out for replacement tuners, if you get the tuners from Hipshot, or Graphtec. Both vendors have come up with ways to mount their tuners onto headstocks without redrilling. Hipshot uses the Universal Mounting Plate (UMP) and Graphtec uses a similar system, but a variation with their Ratio tuners. The Hipshot UMP system uses a pair of metal "universal" plates for acoustic guitars that locks the tuners in place. The Hipshot tuners can be closed (15:1 tuning ratio) or open back (18:1 tuning ratio); the open back tuners are a little lighter. There are also locking tuners and staggered post 6 in line tuners, but as they are intended for electric guitars, they are not really applicable here. I changed over a couple of guitars using this system, and it works well. You can put the Hipshot tuners in really fast, and just put the originals away until it comes time to sell the guitar, then just put the original tuners back on. No luthier required, no multiple drill holes for each tuner post. Only caveat is that the tuner post holes must be 10mm.
I cannot speak to the Graphtec tuners, as I have no personal experience with them, but there are Youtube videos about them.