If the line of the Eureka Northern was the most scenic, it should be rebuilt instead of Silverton to Eureka and truck the engines up to make the run. The cost of trucking the #315, for example, up for a week of operation three times during the summer would be cheaper than building the track up to Eureka. That short haul for a truck move could likely be possible costwise, and expend the track construction expense on the most scenic portion of the route. But you might need the WSL Shay #12 from CRRM to safely handle the grade.
"Rainbow Route" Page 260: Eureka Northern to Animas Forks 3.92 miles, average grade 5.77%, max almost 7%. 85 curves on SN extension, final curve in mill 24 degrees, line began with 32 degree curve 182’ radius in Sunnyside yard at Eureka, 6 curves of 30 degrees (194’ radius). One 40 degree for 100 feet (147’) at mile post 11.97 at Grouse Gulch.