These guys have been busy, but who would know? Check out the gallery for progress shots.

http://www.steamlocomotive253.org/

Is this engine realistic for longer excursions? How will it ride? Or is it better for short distances?

Long, no problem in terms of mileage. In terms of time, we're looking at an all day survival trip, beloved by foamers but anathema to families with small children. I can see the possibility of having occasional all day trips for foamers with runs by, photo freights, etc, but the bread and butter will have to be a less than an hour impulse priced turnaround product for mass consumption combined with special events.

Exactly how do they figure this 0-8-0 has 6000hp?
Seems to me the N&W 2-6-6-4 engines were 6300hp, and this one isn't exactly similar!

I agree that this sounds a little off. I know that 0-8-0 could be strong locomotives. I will not deny that. However, if Big Boy was measured at 6,290 hp, I find it very unlikely that an 0-8-0 could have 6,000 hp.

I suppose you could theoretically get there at a certain speed if you ignore some trivial things like cut-off, back pressure, boiler capacity, total rolling resistance, etc. I'd guess that the actual may top out at about half that number. But then, I ain't no steam expert - more of an internal combustion kind of guy. Maximum drawbar HP of a steamer is almost a moot point anyway since it is speed dependent.