I have to say I like that fantasy NYC page. A surprising number of the machines illustrated there could have been real, including the super Hudson that was apparently inspired by the Niagara (and would have given the C&O L-2 a run for the money as the heaviest Hudsons built), and the 2-10-2 based on a Mohawk that is a good looker. I can imagine that series at work on the never completed South Penn line that eventually provided the bones to the Pennsylvania Turnpike.

I wonder how that line would have looked, by the way, coming into my home city of Wheeling, W.Va. (proposed western terminal), with those NYC fantasy 2-10-2s running parallel to the B&O from Elm Grove (my neighborhood) and rubbing elbows with B&O Mallets and PRR Decapods on the interchange tracks that would have been in the neighborhood of Fulton, where one set of my grandparents lived.

You raise some interesting possibilities. I'm not a modeler, but it would be fun to see some of these "fantasy" NYC engines become models. In fact, one of them did!
http://www.railarchive.net/nyccollection/nyc_4917.htm
(Scroll to bottom of page)