As far as steam goes, when you are dealing with the Loop and the Cut at the Lebanon Mine, keep in mind that was engineered for fairly small 36" guage locomotives, like the #9 was when originally built, or to use an exsisting survivor, the 191 at the CRRM. The engines used there have to meet two criteria not too long , not too wide ; too wide being very important at the cut at the mine stop.
Without having measurements on hand, I would say the RGS 20 would do alright there, 346 & 318 would, C&S 60 would, I think the 430 class engines woudl be too long and too wide for the cut, 491 is far too wide.
From what I have seen of Heavy Freight trains on the Clear Creek Division in teh early days, they usually had between 2 to 3 locomotives so the engines didnt have to be overly large to get the job done.
Hope that helps a bit.
K. S. Wilcomb
GB&L RyCo.
Engineer-ret.