Cast or Alum.heads for racing.
agreed the w2s out flow the edelbrocks out of the box i have never heard of aluminum heads on a cast iron block cracking because of the heat i mean car companies have been putting aluminum heads on cast blocks for at least 30 years and had warrentys to stand behind their work its up to you really i think there is nothing like an oval port small block if its good enough for herb mcandliss and nascar its good enough for me