Agreeeing with below statements.
I would AT MOST just base coat/clearcoat the sheet metal only. Single stage on the engine/cast drivetrain components.
IMHO,there are just TOO many,small moving components to NOT have to touch them up at some interval. Single stage is just easier to re do.
I can send you photos of mine with the cast components done in single stage and the sheet metal done in base/clear,if you like?