A significant factor you should not overlook in achieving a look similar to a 75 or 85 lens at f/1.8 is your placement of the subject relative to the background and the camera position. The influence of these parameters, of the photographer's choosing while setting up the shot, is not to be underestimated in achieving a certain portrait "look".
Using a lens like the 60/2.8 to achieve a look somewhat similar to that of the 75/1.8 will require the camera to be relatively close to the subject and the background relatively far from the subject. The closer the camera to the subject and the farther the subject from the background, the greater the isolation effect and the greater the defocus (blur) of the background. Even using the 45/1.8 in this manner can achieve results which are similar, though not identical, to that achieved with the 75/1.8.
You might do a test, using a set-up as I've suggested, with your 60/2.8. You can create stunning portraits with this lens (as with most good lenses, really) if you do your part well enough. (Careful selection of location, background, lighting, subject placement relative to background, and camera position... in addition to lens selection.) I use my 60/2.8 for general subjects most of the time, rarely for macro applications. And wouldn't hesitate to use it for portraits in place of my 75/1.8. You can make great portraits without the 75/1.8 or comparable lens.
