The new aluminum heads will flow more air and allow your engine builder to increase the compression ratio for your local pump fuel which will give you more power, which choice do you want? Another thing to consider is if you can find someone who needs or wants a set of those heads you can recover some money on them also work
For the best performance aluminum is the only choice up twocents

Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)