You know I think that this would make a great model either as a entertainment park scene or a dummy locomotive.Model trains pass many structures on their journeys ,a movie set is just one of those structures that can be depicted in scale.
I have heard that this kit is subject to warping.This is probably true if left out in the sun on hot tracks,sand,pavement etc....I have tested the plastic myself and it is no more subject to this problem than any other plastic that I have worked with.And yes there are options,one of those being to support the structure before assembly.I think that I would try coating the interior of the larger pieces with exopy,fiberglass or some other warp resistant material.Where the plastic touches hot metal like tracks make a section of the wheels in wood which is a great insulator.
For indoor setting I don't see a problem at all unless you were to put it next to a wood stove or other high heat generating source.When I do my 2nd General I will experiment with this a little further.
As far as availability is concerned just do some networking.I am sure that there are lots of Generals sitting in closets waiting to be built.I got the one that I am working on now for the price of the postage.It was partially started (a small bit of the tender) but no harm was done and the parts were still all there.I have also seen many sell on ebay for less than 50 bucks,new and in the plastic packages.
Personally if I was to do a G scale layout I would do it with a movie making theme of which the General would be just one of the structures that I pass along the way.I would do it as a "out of season" amusement park thus avoiding anything that would move other than the train .Having to make or modify all those figures would also be quite unnecessary.
Sounds like fun doesn't it ?
Once Upon a time.........dioramas by JohnReid