According to my notes, continuous tractive effort for 1203 is 19,200 pounds at 8.7 mph minimum continuous speed, but that only calculates out to 540 hp with might match the 1947 rating. Increasing the horsepower input does NOT increase tractive effort, only the speed it is developed. That also assumes the traction motor cooling system was working at full capacity.
In steam terms - I hope they didn't try to replace a K-28 or K-36 with a "C-19". A diesel-electric will simply keep trying to pull harder as tractive effort is in direct proportion to speed, at least until it either slips or burns up the traction motors. I'm not sure how well the GE main generator is compatible with the Westinghouse traction motors. The White Pass shovelnoses were 900 hp and 24,000 cte, so it is quite possible it puts too much power into the traction motors unless everything got turned down. In the thin air, the traction motor blowers won't be as efficient.