T'were it my decision, out of the three choices, I'd buy the 3" K Frame for concealed carry. 99% of the time I would feed it +P 158 FBI loads and go about my business.
As long as you don't make a habit of pistol whipping assailants the ejector rod should be fine. A 28 would probably be a better choice for buffaloing ner-do-wells...
I personally would hesitate and think long and hard before buying a Ruger (or anything else for that matter) that has already been modified for competition without knowing what else had been done to it, and who had done the work... but would have no problem with any other lightly used 4" Six for open carry, a 2-3/4" for concealed.
But you know what they say about opinions...
Go snag that K Frame before someone else walks away with it.