A few of the Canon models, VT, VIT, etc. did have a parallax correcting pin on the cold shoe, which would raise or lower as you moved the focus from either closest to infinity. Pretty spiffy design.
The best option is to get a body with 28mm frame lines, much more accurate than a 28mm external finder. Or going with wider lenses, such as 25mm or wider as its easier to use external finders on these lenses and get good results through zone focusing and the dof you get with the wider lenses.
If you dont want to drop to much cash, just estimate the frame lines with your M2. I used to do this quite a bit with my Canon VT, VITs. If you are familiar with the 28mm focal length its very easy to eyeball it from the edges of the 35mm lines.