I purchased the French DVD release of this, titled "5000 $ Mort ou Vif" and thought it to be generally faithful to the novel, but not particularly good. "Hollywood" has generally done no good turns for LL in this respect, at least in earlier years.
I've yet to see "Blackjack Ketchum, Desperado" because I can't get past the silliness of the name change, and haven't been able to find "Kid Rodelo" yet. But in later years we've had some really fine films. I wish Tom Selleck would have made a few more in the vein of CROSSFIRE TRAIL.