It's a delicious subject for sure. The production of what are clearly proving popular RTR OO models of industrial steam raises the possibility of 'someone' having a go at this. What particularly appeals to me is that a centre motor BoBo drive of the type now standard in D+E traction would easily fit, with which type of mechanism it would really perform. I was able to adjust a small OO BoBo to run around 10" radius for a friend, handy for compact layouts...