CE
I have a similar engine in my garage on the stand. The original number is still on it and is "Xed" out. It is still legible and translates to a 64 corvette hipo 327. The CE is just documentation that the original was a factory warranty and the engine was replaced. The original was then rebuilt and sold as a replacement crate engine. It is probably a great engine that you have as they probably got it right the second time around.