Partially agree with Steve re just missing the boiler etc which obviously would have been a larger seperate unit – so perhaps it was just split up some time back?
I have looked closely at the photos and feel that it is well built and original – look at the close up photo of the cross head assembly and note the oil channels underneath – a nice quality touch. The description on the site seems pretty comprehensive and it is quite an unusual engine in the complexity for a large model of this type.
The price seems a little high, but saying that its a bit of a one-off, and as such will attract a premium.
I for one would gladly give it house room if I had the chance. Regards