My guess too. Don't think curves are an issue as they did get a Big Boy in the State Railroad Museum. Roseville would work as
Dave stated although the SP Workshop ( a little East from the Museum ) might also work if the 1st slot in the building was clear. That transfer table is not long enough for a Big Boy to get anywhere else.
From maps.google.com:
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Been a few years since we have been there, but the Museum is a great place to wonder around. Ya, you can climb on most of the equipment in places where they want that. Have food and trinkets too.
Do maps.google.com and search for California Railroad Museum, then pan down and left a tad. Looks like there is a Challenger, Big Boy or other sitting next to the SP passenger station.
Later