I like those suggestions. The one issue using a historic car in the trainset would be that the railroad doesn't want to mix wood and steel frame cars when the wood car would be next to the engine. I don't know if rebuilding with steel sills like John Cole suggested would be adequate. A car in daily service should be compatible with the rest of the cars.
What if one of the new cars was a dedicated snack car that looked like an RPO or baggage ? Somebody will have to mock up these cars to see if they can be built on the steel frames the railroad has in Antonito. Would be nice if the snack car had the generator located in a soundproof compartment !
Personally I don't (and didn't) have any input on 053, but am willing to go with the decision as long as it doesn't change mid-way through a restoration project.