Cast or Alum.heads for racing.
The right head will win more races when the engine is built to make use of them. IMO, there is no reaason at all to run iron on a race engine unless the rules say to. W2s are good heads, and the new RHS Magnums look promising. But they will cost more money to get to the level you need. You'll need 550hp on a race car to go way in the 10s. Closer to 600 on a car that does double duty on the street too. J heads are a total waste IMO in a race engine. To match even the RPMs they need port work, seats, guides, and other work. It simply doesnt make sense any more. They did work. But there's much better out there now. Not to mention smaller tighter chambers that no factory head has. So what is your right head? The budget and the ET, plus the current condition of the car and support systems need to be known.