Examining the Bachmann On30 passenger cars it will be easy to convert them to 55n3. The seperate floors on them and the caboose makes only four cuts to lower the bodies:
The windows on the On30 cars match those of Pacific Coast Railway Passenger cars. The cars are 8-1/2 wide x 40-1/2 long in 55n3.
Interesting idea, I checked out the website. IF my math is correct (always a big “if” with me), standard gauge track in that scale would work out to be a hair over 1" gauge??