RAWHIDE KID #111, 1973. From RK #41 (1964). The fence in the back is new, and the speech balloon is completely redrawn (with the same dialogue). That's a beautifully dynamic cover.
KID COLT OUTLAW #173, 1973. From KCO #99 (1961). Again a new fence, plus that coach in the background is added. Actually in this case I think the additions add some nice balance. I liked how they played around with the settings and angles to provide a variety of strong images within the genre.
TWO-GUN KID #112, 1973. From TGK #65 (1963). Yay! This one was pretty much left alone. A very powerful cover with a nice background and a character who would have fit right in on the super-hero books that were taking off when it was first published. My favourite of these three.