Gotta say its an odd choice for an observation, as it seems to be the same car Rivarossi did eons ago and more recently by Kato on the PRR Broadway.
One less drawing room, two compartments instead -- this car has an extra window in the wall at that spot but otherwise is a dead-ringer for the "View" cars. One would substitute on the BL when a "View" car was out for maintenance. MS has the car names on their Pennsy passenger car name sheet.
I wrote an illustrated article on how to convert the View (either Kato or RR version) to one of these cars, but they sat around at RR mag offices for a long time. Still is, in fact ... but then. well you know why...