"I would have built a 15" gauge 5/12-scale version of it years ago except that there are no drawings for it. They burned in the 1969 roundhouse fire along with the ALCO drawings for the Sumpter Valley’s #80 & 81 now SV #19 & 20. I would have liked to built the SV loco as my second choice."
Why so hung up on having original blueprints to make models from when you have access to the real thing? Sure it makes it easier, but you don't need them. All you need is a camera, tape measure, calipers, pencil & paper. That and a budget to take the shop crew out to lunch/dinner for letting you get your finger prints on the engine. :-)
Cheers,
Curtis F.