Like the way you spun it up Luke
Take it the engine is long gone ? Theres a drive shaft to the hydrostat unit which should have a fan on it.
Any single cylinder engine will do ie Honda 8hp plus is fine to power the unit. The old engine was 20hp
The cooler on the front is nothing to do with the tractor, well not on mine?? where do those pipes go??
Just remember, if you get fed up with it I can give it a home