Dalian loco works in China and Toshiba in Japan, IF the D&S had the money, could put new Diesel-Electrics on the rail but it wouldn't be cheap per unit. GE will build new narrow gauge units, they were so miffed that Kiwirail went to back to Dalian with second and third orders.
As for clearances, our 3'6" units are smaller with wise than the -36/37's, I doubt D&S would need any more than 2400hp per unit but would need more than 1500hp to account for grades, altitude and train length on all those sharp curves. The Dynamic Brakes would need to be extended range versions which would lower train operating costs since the majority of the return journey is downgrade, give a way better ride and less particle matter in the air for the passengers to breathe not tpo mention there are the savings made at the end of operations with so much less servicing and manpower needed to support the operation.
Probably get by with one fitter, four drivers and need only five locos to run the whole railroad, the savings would pay for them new loco's rather rapidly.
Of course not many on here want to hear this.....