There are heads that are good for 8BA, other ones for 81A prewar 221, good ones for prewar or post war 239, etc. You will have to settle on an engine to get a better answer to your question. There is a lot to be said about running cast iron heads in performance applications. They aren't as pretty as the cast aluminum aftermarket heads but they can work better than some. It all depends on the type of block you start with and whether it is relieved or not. Running a supercharger also has an effect on whats better than what.