A lot of good advice here and it's all based on actual observation, rather than a definition of the words used to label something.
The 70's *look* was a combination of fashion, aesthetics and the technologies of the day, including print processes.
It is also a purely descriptive term that serves to delineate how these images look different to us today when we are more used to the modern fashions, aesthetics and technologies. It is not really a term that describes how the images *looked* to us in the 70's because they looked much newer and fresher then.
I saw this best summed up in the title of a book; "Seeing is forgetting the name of the thing one sees."
Having said all that the actual images linked to look surprisingly easy to duplicate. To me the Kate Bush images look like push-processed film, blocked shadows and grainy. The other image has a *larger format* feel and is not what I call 70's other than the subject matter. It seems to be a 70's shot trying to replicate the 1870's, (in line with the dress sense of the main character?). The resolution and gradations suggest MF but are possible with 35mm *if* you know how to extract the maximum performance possible from film. Something that won't happen if you send them away to be developed.
Now what must also not be forgotten is that we are viewing all these images on a computer screen and not how they were viewed in the 70's, (or indeed early 80's). So if we take some old push processed Tri-X or HP5 print it in a magazine using 70's press technology and scan that print... Or take a short cut, use modern Tri-X or HP5+ push processed so the shadows are blocked then digitalise it so it shows the limitations of the processes at the time rather than modern aesthetics of contrast and sharpness and I think you will be near. I don't think that the plug-in filters are really worthwhile here.
The other shot though is not one you can duplicate easily with 35mm film. First and foremost you MUST forget about digital methods of sharpening because it is the lack of these that give the appearance of resolution, The other thing is that once scanned and processed you MUST re-size the image using a *soft* algorithm that doesn't overly preserve acutance. It is partly this, the resizing, that can give the image it's clean look when viewed on a computer screen. There is also a lack of clear *mid-tones* as though the interval of middle-grey has somehow been subtracted:
If I showed you the full sized scan it would look far more like a grainy 35mm shot.
