The Heritage marine engine is similar to that supplied for use with the Midwest Fantail launch, but with one major difference (and a few minor ones). The engine unit itself is very different. Minor differences in the boiler are the chimney and the safety valve. It also has a name badge fitted. The base is also different. I don't know if these are how it came from the factory or if it was modified by a previous owner.
The boiler is a traditional vertical type with a single flue. The burner supplied is designed for Sterno. The engine itself is a fairly standard marine type vertical single acting oscillating cylinder. The cylinder and frame are machined brass castings. The piston, crank and flywheel are turned metal. The dimensions of the boiler are 2 1/4" dia x 2" high. The cylinder is 3/8" bore x 1/2" stroke.
As acquired, the boiler appeared to have been fired but the burner tray was clean. I assume that another tray was used for firing by the previous owner. The performance under steam was disappointing and the burner appeared to be starved of air. I have since modified it to improve the air supply.