I am currently making this engine. It has actually progressed beyond this photo, and is now complete except for the steam connection, installation of control valve, and painting.
It is a Bolton No 12. Based on an engine and pump from near Maitland NSW. The original was rated at 16hp.
This small version has a 50mm bore and 100mm stroke. It weighs 72lbs (32kg)!
It has a copy of the original James Watt governor, and a version of the Watt parallel linkage between the piston rod and the beam.
It has taken me about a year to machine the castings and make the myriad of parts which comprise the engine. The flywheel is 14″ (350mm) diameter. The base is not authentic, but I chose it to not conceal any parts. It may eventually house a condensing unit.
The plans and castings came from EJ Winter Sydney.
Stuart have a similar although smaller version of this design, which I am informed is a copy of the Sydney design.