[Oldsmaniac]

If you want to keep it stock the 350 is a good engine and less thirsty for the high priced fuel we have these days. A 455 will give more punch be more thirsty and will require some adapting with brackets, maybe a bigger radiator, heavier front springs, and a turbo 400 trans is recommended. Why build a smogger though? The 455 needs no more smog controls on it than your 350. The later 455's have lower compression ratios and the heads are designed for unleaded gas.....both of these aspects are good for a street engine.