Reply to "Curious: Would This Be Possible?"

I've considered the same approach - blending AM and Lionel steam with AF cars - in an otherwise mostly-scale layout application.  It's the darn freight rolling stock that's been the issue for me in my desire to do scale S -  the SHS / PRS boxcars / reefers are so hard to locate for early 40s railroading - especially ATSF - but there seems to be plenty of the AF rolling stock out there that would "work".