Well the lt1 and the ls1 arent technicaly 350s.no parts on them will interchange with the old school 350,and the difference between the ls1 and lt1s are not just the heads but also the blocks.the lt1 has a cast iron block and aluminum heads,as the ls1 has an aluminum block and heads.well thats about all i know about the lt1/ls1 engines but there are more than a few people on this board with real knowledge of theses engines so ill let them educate ya later,Ray