I'll bet the lines and carb are original. The engine paint seems to be highly oxidized from age and cheap factory paint. The originals I have seen which have been protected by a heavy layer of oil and dirt have a much more lustrous, shiny appearance once cleaned up.
Even though it is absolutely "original", I would not use the engine in the 1.5 mile truck as a pattern for painting a 55 engine.
Carl
It is abit dusty. I think the word oxidized is over used when it comes to paint. What messes up paint is sun light and uv rays. This painted item was far from uv light from the sun, as it was under the hood and in a garage or storage building. If the dust and dirt was washed off, which I would have done if I would have got it you would see the best example in modern days of what the color of the engine and other parts should be.
