Denver to Dotsero via Moffett tunnel: 166.8 miles
Denver to Dotsero via Pueblo & Tenn. pass: 341.9 miles
Distance penalty: 175.1 miles
First passenger stop beyond Dotsero is Glenwood Springs, another 18.2 miles.

Schedule time between Denver and Glenwood Springs:

CZ via Moffett tunnel: 5h13m WB, 5h25m EB
Prospector via Moffett Tunnel: 5h30m WB, 5h45m EB
Mountaineer via Moffett Tunnel: 7h05m WB, 7h10m EB
Royal Gorge via Pueblo: 11h25m WB, 11h00m EB

The Mountaineer was essentially a local. Even allowing for the more relaxed schedule of the Royal Gorge, it can be seen that the time penalty for operating via the Royal Gorge / Tennessee pass route would be at least five hours, probably more likely six hours, even if the speed limits of 1948 still prevailed. Remember, Denver to Pueblo is a very heavily used line for coal trains, so with superelevation reduced in the curves as well as train interference, the elapsed time over this line is probably a lot longer than it was in 1948. Therefore, a time penalty of eight hours or more is likely.

The original UP across Wyoming is still a very fast piece of railroad.

Therefore, for purposed of achieving some reasonable approximation of the schedule, to take the original Union Pacific across Wyoming is the only reasonable route.