I don't think that "restoration" was quite the right word here. Conversion might be better. The movie crews work fast, but it seems to me that the whole project took a couple of weeks to complete. Notice that in the first picture there is quite a bit of snow on the ground, and by the second it is gone and they still have a ways to go on the conversion.
As far as the interior, the Hinman was very much a simple coach with throwover seats, as Richard indicated. Not sure if they were original to it. A couple of years later when it was used in White Buffalo the old seats were back in but the exterior wood sheathing was still in place, but painted different.
"Time spent with CATS is never wasted." -- Sigmund Freud
"Nothing endures but change." -- Heraclitus
"C'est le meilleur des mondes possibles." -- Candide