I agree that an A-B-B set of WP’s from 3rd Rail are a bit pricey. Probably north of $1,900. Remember they do not offer non-powered F-units.
The same A-B-B combo F3’s from Atlas will run under $1,500. Again all three will be powered. In ther effort to make the second run of The California Zephyr special they only offered powered units for al three roads; CB&Q, Rio Grande and Western Pacific.
Will the Atlas combo be able to pull the 12-car California Zephyr up a 2% grade. YES. I would be willing to bet they could pull 24 CZ cars up that grade.
Slight problem, these units will not be available until Feb 2019. So you have a couple of months to pony up some more $$$.