I think if I had to pick just one engine to prioritize for return to operation it would be D&RGW #223. The reason I would focus on this engine is the other larger K class engines have an economic and operational incentive for their owners to restore as they are capable of hauling tourists efficiently. Therefore those that can will likely be returned to service at some point and in the mean time other members of these classes have or will be operated in the future.
Smaller engines like the T-12 & C-16 class don’t make a lot of $ense for operations when they are limited in how many cars they can handle on some of the remaining RR’s. This is the main reason why private funding is required if these lighter engines are going to be restored for operation. Further, next to D&SP #51 (1880) and D&RGW #346 (1881) #223 is one of the oldest surviving engines (1882) and a Grandt built locomotive also. No other members of the C-16 class are operational. The Golden Spike Chapter of the R&LHS society has been working on this engine for a number of years in Ogden, Utah and as the #315 group has shown, it is possible to restore an engine with volunteers and donations. Let’s hope they can persevere and then let her stretch her legs on some of her former Colorado lines.
Otto Perry photo from DPL OP-7439 7/4/1940 Gunnison, CO