Welcome to the Forum,, I agree with 'street 'need more info as to the guns "configuration" and just what is "good condition" and "a little bit of holster wear" ...condition is everything when it comes to value, and the prices he quoted are more in line with a collectible gun, "good condition and holster wear" falls a bit of those kinds of values..................got any pictures??? would help make a better evaluation......and "extras" like the box and paper work???
as for any "extra" cylinder, as 'street' noted and I agree, doubt if it came with one.....you can always have the bore 'plugged ' ( gauged using something like Cerrosoft) for its bore diameter.....1960 is right at that 'transition' point in time when the 22 Magnums came out and were actually put to use in a revolver, and the first ones ,at least by Ruger ,were "Magnum" marked as such, convertibles came into being shortly during AND after.........
you can always contact Ruger, and apply for a letter as to just "how" ( configuration) your gun was shipped, that's about all they will tell you, as well as the ship date..........