When I started doing macro work (back in the film days) I started with a 90mm Tamron (good lens BTW). What I found was that the working distance was too short. I could not get close enough to bugs and the field of view often included too much background. As soon as I could afford it I bought a Nikon 200mm f4 Micro lens. The field of view is great for framing and the working distance is long enough that I don't scare away bugs every time.
In your case a 60mm may have the field of view of a 90mm on a film camera but the working distance for minimum focus does not change so your working distance will be even worse than what I experienced. I do not think you will be happy.
I recommend that you consider a longer lens like the Nikon 200 or the Sigma 180 (I have experience with the Nikon but not the Sigma so I have nothing to say about how well the Sigma performs). You will get an working distance that will be as good as you can get and even narrower background framing than what I get on my D700. A lens like that can be a bit pricey, so, alternatively look at a Tamron 90mm or a Nikon 105mm instead. My experience with the Tamron is with the older MF version but what I have heard is the newer ones are even better.