For precison viewing/composition in tight photographs, nothing beats an external finder. My 85mm Canon Finder is great to use, it is the earlier version for the VT cameras, with the ball-bearing on the bottom of the finder. So on my Canon P, I use it with the Canon "Coupler Finder", so it works (with parallax lever) on my later Canon bodies.
Here is the whole thing put together, with my 85mm F1.5 Canon. I have a roll of Panatomic-X film in this body, that I need to finish