I had a pair of those Heislers back in my 2-rail days - very nice models. I had the standard gauge versions. Ran very smoothly; I wish I had kept them.
If you placed one of those Westsides next to a Bachmann On30 Heisler, again it would dwarf the Bachmann.
I would recommend searching out one of those Westsides for anyone wanting a standard gauge Heisler at a relatively reasonable price.
A 3-railer could add a small mountain division using 2 rail O gauge track with maybe a switchback-type plan to conserve space. I never experimented to see how tight a curve the Westside could take.
Jim