To begin, gallopers is a British name for roundabouts which revolve clockwise with horses which go up and down as it turbs. Carousel revolve anti-clockwise and are American or European.
You might like to check Doug Foreman Engineering website as he sells plans for fairground rides in various scales.
If you are within reach of Liphook in Hampshire I could arrange to let you examine the set at Hollycombe where I have been a volunteer for a very long time and drive the gallopers.
I look forward to following your progress
Sean