Evening LTx family, so after doing some research here (and i do appreciate the help). Im a moving forward to the very heads themselves once i get them to a machine shop. I plan on keeping my LT1 bottom end and cam stock (96 impala SS btw). Whats usually the maximum port job i could have done to the 643 heads with a stock cam? Thanks. Im still learning how all the internals works, so please excuse my silly questions. LOL.

 

Your talking iron heads? You should upgrade to the aluminum heads and camaro cam, than port those.

 

643s are aluminum lt1 heads.

have a look at lloyds site. le1 would probly be best for stock cam. you would want to compliment the heads as best you can if your not going to go with a biger cam. exhaust, headers, intake port and gasket match, cold air intake but im thinking you have some of these. 1.6 or maybe 1.7 roller rockers with valve springs to handle the change. you would need to check the push rod length to make sure they are right. a cam matched to the heads and such would be the best and right way to go.