Glad this post came back up, as I had read it when Mike first posted it back in April, but just failed to comment back then. First off, Mike, this is all very cool work. Regarding the Bachmann Hudson, one of the biggest details that needs to be changed to accurately represent a post-1946-ish J3a Hudson is changing the Elesco feedwater heater with a Worthington heater. Detail Associates makes the Worthington heater. It will be a little tricky to grind off the round ends of the Elesco, as I think that part of the shell is metal? And then you'd have to match the gunmetal paint coloring that they used on the smokbox, although that shouldn't be too big of a deal. Anyway, considering how much this change in feedwater heater altered the look of the front end of the Hudsons, I think it is kind of an important detail. One of these days, I'll eventually get around to doing it on my Bachmann Hudsons. And if you should take this little project on, I think the Detail Associates part tends to sit a little too proud, so the bottom of it also needs to get filed down a little. This is kind of what I remember from when I made this change to a Con-Cor Hudson many years ago.
I hit post, and then remembered I meant to answer the question regarding the paint scheme for the coaches. By 1955, either the green or two tone gray schemes could be seen on the heavyweight coaches. The NYC started to paint various heavyweight cars into the two tone gray scheme in the mid-50's as they shopped the cars, but they also didn't really make a big push to try to do them all, as plenty of heavyweight cars lasted in green until the end.
Hope that helps.
-Brian.
Thanks
@Brian M ! Worthington FWH is easy enough. Thanks for confirming my choice of coach schemes too. I can weather these out now.