In the movie they Might Be Giants, a delusional jurist explains that he loves westerns because they show the clear delineation between right and wrong, which is when I realized why I vastly prefer mysteries to westerns; I like a more complex world view in which the good and evil dichotomy is not so apparent.
Station West is a rather unusual movie in that it looks like a western and has a western-themed score but in terms of story and acting is more akin to 40s tough-guy detective flicks, with more moral ambiguity than you'd see in a John Ford movie. It's not dark enough to be called film noir, but it has some of those elements, and the relationship of Haven and Charlie is very Hammett-Chandleresque.
The movie is enjoyable and briskly paced, with good performances and decent dialog. At the same time, Powell is a bit too unsympathetic for me, with a fairly callous disregard for the results of his actions. And the plotting is a little lazy, with that convoluted, poorly explained style you get in most of the Philip Marlowe films. But if you like 40s detective movies this is a good bet.