I don't want to insult anyone but I think the American engine's are very ugly.
I love the elegance of the Victorian and Edwardian era railways.
The way I would have done it is buy getting the Dean single and recolour it with a couple more pipes in brass and use a cog the same size as the driver wheel and stick that on. Maybe a small clock on the front of the smokebox and take away the front of the wheel arch. And then name the company Great British instead of great western. Just an idea
In fact I will model it myself at some point.