I'll like to get more power out of my '72 350 Convertible. Some say it's easier to drop in a 455 but I'm thinking along the lines of the doing a rebuild/upgrade using the engine spec's from the Olds Rally 350, I believe they made around 310 to 350 hp with stock cast iron exhaust manifolds. Does anyone know where I could find these specs? Thanks, Roqetman!