James has done some great work covering the history of the Ringo series on his website, so head on over for the lowdown. I don't have much to add other than to show off a cover scan of my own spiffy copy of Ringo #1... (It is a K.G. Murray #1 issue after all, right...? And it's not as if there's plenty around to choose from, right...?)
I can at least confirm that a couple of the Ringo stories are reprinted as Gringo in the Gredown issue Gun Western. "The Secret of the Swamps" and "A Cross in the Snow" in Ringo #1 are retitled "The Swamps Secret" (sic) and "Cross on the Snow" in Gun Western.
Gun Western also includes another Gringo story, "The Kidnapping".
And yes, this spiffy copy is mine too!