The 491 was cosmetically restored and is now at the Colorado Railroad Museum. Many of the gauges and valves in the cab will need to be replaced, It has not run since the 1960s and that was the last time the boiler was inspected. An extensive rebuild would be needed.
The 494 and 495 were officially retired in 1962 and made their last runs sometime before that. My unofficial opinion is they would have to be rebuilt from the gorund up, aka C&S No. 9 only probably more extensive. It would be cheaper to build a brand new locomotive.