One of the more interesting re-engineering problems with a Mason Bogie will be how the running gear will be attached to the boiler. The big feature with the design was the engine "unit" swiveled under the boiler, and was attached to the bottom of the boiler barrel with a swiveling connection that included the steam connection to the cylinders. The entire pulling force of the locomotive went through this connection to the boiler barrel. The load was transferred through the boiler to the rear frame extension to the drawbar on the back of the tender.
Today, no one is going to let you put the pulling force of the engine through the boiler.
The guys as the WW&F had the same kind of issue with their WW&F #9. They solved it by creating a cradle around the firebox to transfer the pulling forces around the boiler. In their case, the running gear of the locomotive was rigid to the boiler and didn't move.
Making a Mason Bogie so it will "bogie" will be an interesting engineering exercise.