If your going to replace them don't use steel The harmonics from cap walk will crack the main webbing and you won't know it until that block fails
Aluminum caps don't do that is what I have seen so far
Your better bet is to find a good race block or a good 400 block withe thicker main webbing and build it with good caps and so on, they tak ea lot more power and punishment than any stock 440 production car block made to date