Madlove, I don't know about running tightly side by side, but I’m in the process of revising my ongoing ceiling layout build to remove the O-63 inner loop and replace it with a HO loop inside the O-72 track. The HO track in the photo is the 22-inch radius Bachmann E-Z Track that came supplied with the Amtrak Acela box. I placed a 9-inch straight in the middle to bring it as close as possible to O-63 width for comparison test around the corners. I won’t be using the Bachmann track but will be using Kato Unitrack. With the HO in front, it's a reverse forced perspective, but that is what is needed on a ceiling layout when trains are viewed overhead at an angle otherwise the smaller scale train (whatever the combination of scales) would never be seen.
