GTR 1120 replaced 2543 on this morning’s mixed train (45) and returned on the noon passenger (44). Still in her original Southern Railroad livery, the test run revealed some improvements are in order to both track and engine.
In particular, the engine truck needs to be heavier if it is to find its own way down the track. I might also re-design it to flex a little to accommodate changes in level.
The tender is also much too light and leaps for the ditches at the slightest provocation. I suspect it’s largely empty, and it should be straightforward to add some weight if I can figure out how to take it apart.
The contraption barely fits on the turntable. However, it has more than three millimetres of clearance as it squeals around my tightest curve. So I should be able to make a shorter coupling to buy a millimetre or so on each end of the turntable.
Overall, I’m happy with the outcome so far.
Pembroke:87 
I think that’s the first time I’ve seen a video of your trains in action,
Ha, you’ll have to come out and see for yourself!