I think the reason it did not achieve this goal is kind of obvious, number one the crossover of fans is not that big, I don't think the world was ready, nor may ever be, for a western themed thriller film. In fact very few genre's can successfully be mixed with western. The only other crossover western movie I can think of right now is Westworld. But that movie is far more successful at it's goal than this one.
Other reasons why this one might have failed: it's kind of heavy on the dialogue and lacking in the suspense. Sure, there are some cool suspenseful scenes in the film when it's done well, the soundtrack is good and ominous, but overall it's pretty slow. The good thing about Jaws was that feeling that any moment the shark could arrive, the ocean was huge and vast, they were in the enemies territory, etc. From the beginning of this film, it's made pretty clear that when they will finally face the buffalo, it will be on their own terms.
Speaking of facing the buffalo, here is the plot: Wild Bill Hickok, played well by Charles Bronson, is having nightmares about a white buffalo. So he decides to hunt the bastard down. He comes to some town, picks up an older man who he mostly just calls "old timer". Hickok and Old Timer then cross paths with several Indians in a fight, and help out an outgunned Indian named Worm (played not that great by Will Sampson). So, Worm is also out for the white buffalo. Apparently it killed his daughter a while back. So the three of them hunt it down, and for some reason call it "spike".
That's pretty much it, it's not a complicated plot at all. It looks like it may have been low budget, simply because the film looks like it could have been made for next to nothing.
Of course, one cannot write a review for this thing without talking about the buffalo machine. Oh, the buffalo machine. You know, if they had only showed face shots, or if they had somehow actually gotten a buffalo, or if they had done just about anything else, this movie probably wouldn't be remembered today. It's pretty forgettable. Except for that insane, laughable buffalo machine.
You know those mechanical bucking bull things that people like to get totally drunk and then try to ride in western themed bars or movies? You know the ones. Well, imagine one of those, that only goes up and down (it doesn't turn or anything) on a fucking obvious track, sliding towards Charles Bronson. It's a pretty bad effect, and you see it plenty of times.
Now, they must have known it looked bad. They definitely try to shoot the buffalo in close ups and only show the face. But the face it kind of silly anyways, it's just not AS silly.
So that's why this movie is remembered....pretty much. That's why I saw it. All in all, it's not a terrible movie, it's just not that good. It's got a mechanical buffalo, but other parts of the build up are done pretty well. Actors are generally good and cinematography was well done.