As a followup: Walthers had the NYC car on sale for $19.98, so I went ahead and ordered it, and it arrived on Monday.
Here it is next to the mockup-so-far of the Kankakee station, for a size check:

I'm compressing the station to about 80% of actual, and wanted to make sure it still looked reasonably large relative to the car. I think it's going to work out.
Here's a closer look at the station:

This is actually the side of the building that faces
away from the tracks, but I started with it because I have better photos. I'll have a chance in late August to get more shots of the track side.