I know many others have adapted these On30 cars to S scale. I had some years ago, converted them to S gauge trucks and then promptly sold them off. I just acquired this matched set of Royal Blue cars off the big auction site. They had already been converted and were illuminated with AC powered Grain of rice bulbs. With Kaydee couplers pre installed all I did was substitute an AF compatible coupler on the front of the combo car and mated the train to my American Flyer B&O Mikado. (closest thing I have to "Old Timey"). The set contains a Combination car, Coach and Observation car.
The cars might scale out a wee bit tall but the train looks great, is well lit and runs smooth as glass. These cars have wonderful detail and will readily accept passenger figures if I ever locate the proper size figures. I'm still trying to decide if I should illuminate the drumhead on the obs. car but I may leave well enough alone. No sense tempting the fates with all the fine detail on these cars.
If you have a modeling need for some "Old Timey" passenger cars on your pike these cars might just fill the bill.
Mark