The articl I have states that the engines were "390 hp out of the crate" so I would agree that they were service replacement blocks. They then installed a ram air cam and heads from a ra 400, cc'd the heads, heat riser blocking gaskets, thin head gaskets and a recurved dizzy and bigger jets in the carb. The engine is rated at 450hp and 465lbs./ft at 3600 rpm. What a beast! The car in the article ran a 12.55.