upguy,
To put the name " Sumpter Valley Railway" on the tender of a standard gauge 2-6-6-2 would be a sacrilige, and Mantua already did that !! They did Uintah # 50, and 51, and SVRY #250, and 251.
Shamus,
Happy to see you found the Mantua 2-6-6-2. That is basicly the same engine I had in the photo of the logger's caboose. I didn't have a diagram of mine when I rebuilt it as the Shinnecock Hills engine, but it is fairly straight forward in construction, and as long as you keep the parts separated it should go back together easily enough.
I don't remember if I got a "parts list"(exploded diagram) with the engine or not. I'll look, if one came with the engine, I have it.
Pete