This was likely the Dulce San Juan that lasted a few months after the San Juan was cancelled from Alamosa to Durango. This one ran from Chama to Dulce. Don't have the historical data but am sure others do.
The whole point of doing a charter is to recreate something that actually happened. If you are going to run 169, then you need to know when it ran over Cumbres, and what sort of trains it pulled.
If you are not trying to be authentic, then any old dogs breakfast consist will haul some folks up the hill for a merry old time.
Greg
PS I don't know my history on some of the older power like the 169. I guess most of us think in terms of the 40's as the heyday, since the San Juans still operated then. While I relate more to the 60's cause I was out there then, the passenger trains were long gone except for some railfan excursions.