I was thinking of doing this a couple of years ago. I was going to start with new Menards 0-42 track (already purchased), Going to order 36" O gauge straights then purchase the standard gauge inner and outer rails/ties/insulators from US track.
I see that you are starting with standard gauge track and adding O ties.rails and insulators.
Is there any draw back from starting with O and adding the standard gauge rails/insulators/ties?
I will be using new materials.
Figure I ask as you have more experience on this as you are making it work.