I have edelbrock rpm heads on a 493 big block that went 9:53 at 141. I wouldn't waste my time or money on cast iron heads when the rpm's are so cheap and flow so good.
Reguardless of your opinion of metal material for your head choice, this is what the thread is about! Doing what you can with unported heads. Steel or aluminum.
You listed your achievement minus what else it takes. Tell us about your stuff!
Help a MoPar brother out!