I am able to get my hands on a great set of iron LT1 heads of an impy from a friend for only $40. The question is will the iron heads flow more air than the stock heads (I will port the iron heads, not sure how much porting) and will the airflow be enough to offset the extra weight? Thanks for the help guys.

 

In stock form the iron versions actually outflow the aluminum versions. But if you're comparing ported to ported, there is no reason to believe that the iron heads would come out on top. Since you have to port anyway, I would do the aluminum. Keep the 50 pounds off the front end. Plus, aluminum heads allow higher static compression due to the increased amount of heat pulled from the combustion chamber.