My earlier comments are strictly related, and only applicable, to this specific project.
While I do not feel that it is viable, it certainly is not impossible. Very little is "impossible!". For a project of this magnitude you would like to have a few items established very early on: A realistic overall cost, considering current fabrication costs adjusted for expected inflation, a properly equipped place to do the actual erection of a locomotive of this size and complexity, and a place to run it.
Yes, I am aware of the successful new steam locomotive constructions both here and in Europe. With the exception of the Tornado, these are small locomotives well suited to be built in a smaller shop. Good recent examples are the rack & pinion locomotives from SLM Winterthur for the Brienz Rothorn Bahn (Switzerland) and the narrow gauge locomotive from Meiningen for Baederbahn Molli (Germany). The nice thing about Meiningen is that they were both building and overhauling steam locomotives for the East German railways until late in the game and continue to be the go to place for heavy overhauls and new large boilers. There never was a hiatus, so the knowledge base has been maintained.
While Tornado is certainly larger by an order of magnitude to the above listed small loco's, it still pales in size to a T1, Similar relationship between the required sizes of the needed fabrication shops. Once again, not impossible.
It boils down to size and complexity and the effect it has on cost and ultimate viability.
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I would like the T1 Trust to succeed, the last thing we need is a project such as this to fall flat on it's face late in the game. But they certainly have their work cut out for them.