I just learned from the a similar thread over at the Team Camaro website that the engine is a real one of only 602 Z28 engines made for 1967 and one of only a handful of "MP" A.I.R. California Emissions (smog pump) engines bult.
http://www.camaros.net/forums/showthread.php?t=178858
They also determined that the original 1967 Z28 that came with this engine has in fact survived and is an original Los Angeles built, original paint red RS Z28 that is missing its engine. The car was built in early May of 1967 and this engine was cast on March 10, 1967 and built on March 21, 1967 so all of the dates line up as well. They are trying to contact the owner of the car now to see if he has any interest in the original numbers matching 302 engine from his car.