I'll vote for the restoration of wrecked-and-stripped D&H Alco PA hulk #16 to pristine cosmetic condition inside and out as ATSF #59L, complete with stainless side panels and warbonnet paint for display at KCUS museum at the behest of owner Smithsonian Institution. (Oh wait... hasn't happened yet!)

SP 2467, "pet" of the Oakland roundhouse, to its working appearance by the Pacific Locomotive Association. A long-running effort started by SP hostler Charlie Hoyle in Harrison Park, with the actual restoration completed under Errol Ohman at the Oakland Army Base. A quiet, first class effort in the field of "big steam" restorations, and done entirely outdoors in about a half-dozen years.