I have a 105 of almost exactly the same age as that one, and it's a long time favorite. I converted mine long ago, and it was not terribly hard to do, using an approach similar to Richard Haw's. I did the further milling required to make the lens 100 percent compatible with some early AF cameras that have a min. aperture switch that pushes sideways (N60, Fuji S1, etc.), but for any camera that has an AI follower this is not needed.
One thing worth noting, though, is that there is a little spring attached to the aperture ring, and it's a little tricky to disengage and re-engage that spring when you take the aperture ring off. Not every old lens has this, but the 105 does. If you know in advance that it's there it can be done without huge fuss, but if not, you can stretch it on removal. It takes a bit of fiddling to re-hook it. If you're not comfortable with this, I'd suggest sending it out.
Last I knew Vermont Camera Works (in Pittsford, Vermont) did the conversion for a reasonably small fee. I don't know if they do the min aperture part, but they probably would if you need it. Dave, the boss there, recently de-fungused my old 400/5.6 lens (which he said was wickedly complicated inside), so I know they do that too. Might be worth an email.
p.s. I would add that newer low-end bodies, such as the D3xxx and 5xxx series, though they have a minimum aperture switch, are not harmed, because that switch is now pushed down instead of sideways. My D3200 will take nearly any Nikon lens of any age, converted or not.
