Is it a "Single Six" a "Super Single Six" (adjustable rear sight with Patridge type front sight) or a "Single Six Magnum"? In that Serial No. range, there were "Magnum" single sixes produced.... it would say "Magnum" on the barrel or frame (I forget where it's stamped).
The value would depend on the model, and even more, the condition (stated as % original finish remaining). Any non-factory work, refinishing, or shoddy maintenance (like buggered screwheads or gouges) will drastically reduce the value. Also, has it been converted to the transfer bar mechanism by the Ruger Factory.... and, if so, do you have the original lockwork parts?
Need all the answers before I can put a value on it.