[JoeC]

The "original engine" is one of those terms that has a lot of emotion but not much logic. You can use NOS or exact repro parts on the car but people get emotional over originality of the engines. It is acceptable to change body panels, the interior, brakes radiator, gas tank, dash cluster, etc., but a replacement engine will subtract value? If the casting no. and vin match the car, and it is correctly restamped and has proper broach marks, etc., and nobody can tell the difference between the replacement engine and the engine in the car, then I don't see why the restorer just doesn't call it an "exactly restored engine." Many restored cars have "exactly restored engines" that magically become "original engines." When you talk to original owners of any solid lifter big block Chevy car they laugh about "original engines." These cars would rev past the design limit of the valve springs and other parts and many dropped a valve and blew up. Ninety percent of the original owners I have talked to said the engine was replaced within three years. One Yenko Camaro got a "window" in the block on its first night of opperation! There are some "real" original engine cars but it is as rear as original paint, in my opinion. It is better to have the original rear end on a COPO car because you can at least verify it by disassembly. Today an original engine is difficult to verify so you have to rely on the accuracy of the history of the car and the honesty its past owners.