K2, I really liked your story. It's a neat plot, and I thought the atmosphere, voice and imagery excellent, hence its appearance on my shortlist. But the issues I saw with it -- that stopped it short of being in the running for a vote -- aren't solved by the amended version, save for one point, and in some cases I preferred the original wording to the new version.
I'll do a nit-pick, as that's my forte, and I'll use the revised version. Most of the things I'll point out are quibbles over punctuation or suggestions/personal preferences that undoubtedly wouldn't worry anyone else. The big issue for me was a failure to control your tenses -- as I read it, since the opening starts with Joe about to make the climb, you want that in present tense. If so, the gunfight and everything that precedes it takes place beforehand and must therefore be in past tense, and I'll deal with it on that basis. If I've got that wrong, and you wanted something else, let me know and I'll try again.
Near forty times I watched Roy Cobb walk up that the ["that" gives the impression of being distant in time or place; as an alternative in present tense use "this"] hill. No cut stone or crosses of iron to lean on, [comma not semi-colon] just scraps of ragged [since "ragged" is linked with "rag" as in cloth, for me it's not the best adjective for wood -- I'd suggest rough/jagged/splintered] wood with maybe a name scratched on it them. [to accord with "scraps" not "wood"] What did Cobb say up there, [the revision, changing it to ellipses, doesn't work for me, and a comma is enough] alone, with only the murmur of a prairie zephyr to answer? [for me the original was far better: (1) "murmur" and "zephyr" are both soft words and the relative sharpness of "whisper" and bleakness of "wind" are better for the atmosphere and Joe's character, and the "wind" in the next para is far enough away not to worry about (2) they don't sound like words in Joe's vocabulary (3) the extra "a" required adds length and upsets the more staccato rhythm you're establishing], No point guessin’, [if the italics are to show thought, it's not needed since the whole thing is in his thoughts, so just serves to create distance] now it’s my turn to make the climb. Marshal Cobb waits in silence, and I wonder what I’ll say.
Save for my spurs, bustling Dodge was hushed ["hushed" alone means the town hushed itself, not just that it was quiet. It's an active verb which only works if the first clause is deleted -- he's not part of the town, so the "save" can't relate to it] when I strode out to the street. Just the burning sun and stinging wind bear bore ["hushed" and "strode" were fine, both in past tense; "bear" = present tense] witness to Marshal Cobb and me. [this alteration is right -- the "I" was incorrect] This day was had been [this needs the past perfect as coming before the day of the fight] long in coming and I’ll I'd ["I'll" is future tense, so wholly out of place in a past scene, though strictly even "I'd" isn't right -- it should be something like "I wasn't prepared to wait longer" which is too much of a mouthful!] wait no longer.
“Joe Buck, you come on now. You don’t have to do this,” Cobb pled [you've reverted to past tense here which is right, but just points up the oddness of present tense before and after] in his buffalo-grunt-like [really it needs the whole thing hyphenated as it reads very odd otherwise, but it's ungainly with the double hyphens and I'd suggest simply removing the "like" as it's clear enough without] voice.
[This is a great paragraph, but is all in present tense and needs to be in past tense unless you make changes to the whole structure] The hell I don’t—it’s my time now— [again I prefer the original here as for me the em-dashes don't work] his days are done and like a hot brand set to hide, this isn’t over till the smoke clears. [I love the imagery, though perhaps "you can't see how it ends till..."? But for me it's in the wrong place here] I’m young and quick with a heart fired by his worn-thin [hyphen needed] reputation. He’s old, large, and lumbering; a big iron and long draw. His begging [I prefer the "beggin'" of the original] eyes just make me madder. [semi-colon wrong] We’re burnin’ daylight; [semi-colon here] I got drinkin’ to do.
[again all in present tense and needs to be past] My short Colt doesn’t scrape leather as I cock on the draw, pivot, and fire. Crack-a-thunder, a dull thump, and it’s over. Lord, I’m fast. [I love that line]
So, I make the climb like he always did and [I prefer the original with no "and" and a new sentence here] when I crest the rise, I see it. A heap of hard clay abreast a long hole in the Great Plains, [I have to confess this really confused me on a first read as the "long hole" and "Great Plains" made me think something yards or even miles long and I couldn't fathom what it could be! Perhaps "deep hole" and surely it's in the graveyard, not in the Plains itself, so perhaps just remove the last few words] Marshal Cobb there beside it.
“Joe Buck, I’m sorry you chose that way. Ride well.”
Oh, so that’s what he says, and without even a whisper, [I see you want to link up with the first para, and in that case I'd make it eg "without saying a word"] I fade into the light. [good ending]
Regarding the tense problem, there are two obvious ways to proceed -- make it chronological, so it's all present tense, but that mucks up the first para, or put all the middle section into past tense, though to my mind there are some paragraphs that just wouldn't work as well that way. An alternative would be to keep it all in present tense, but split it into three scenes, then either hope people tumble to the fact the middle scene is his memory, or make it clearer eg by some kind of introduction to it or putting it all into italics.
By the way, you'll see I've suggested you remove an "and" or two. Strictly the sentences aren't then grammatical, and over-used it's something that grates on me, but for occasional use it's effective in speeding up lines, so keep it as a weapon to use sparingly in cases like this.
I've just re-read Joshua's take on the relative merits of the first and second version, which shows just how subjective these things are as I think I disagreed with most of what he's said! The moral is, you'll have to assess what's said and the reasons and make your own mind up. (But I'm right, of course...
)
Anyhow, as I say, apart from the tense problem my comments are mainly niggles. It was a good story, well told.