The first question would be: Would these be available as both scale and Flyer/hirail? (Be warned, there's a lot of Flyer folks that won't consider cars that won't negotiate R20 [40" diameter] traditional curves.)
There really haven't been any full length streamlined passenger cars made since the American Models (fairly basic) cars from the mid-1980's.
Would these cars be on par with the O scale GGD cars, or as aluminum shells minus interiors? I know cost would depend on reservations, but is there a guesstimate as to cost?
There's few S scalers over here on OGR, I think I'm about the only one left that posts regularly...
I cross posted your opportunity on the S Scale io (formerly Yahoo) board. I don't know if you have access to Facebook, (I'm not on FB) but there's an S Scale group there also: https://www.facebook.com/groups/Sscale/
I personally would be interested in the Super Chief.