I do not own, or know much about a "Modern Day" 35mm SLR.So unless need interchangeable viewfinders or focusing screens skip the F2 and 3 and get another N90 as backup. I know that the military and AP issued N90s, rugged, pretty good AF, fast motor drive, had the features needed by most pro's, likely cost Nikon F4 and F sales. If you want manual focus body, get a FM2 or 3.
Why is it no longer (or maybe it is) a concern to be able to change the Focus Screens.?
How common was it, for the majority of 35mm users, to change the screens circa 1975.?