10+ years ago, I went 9.30's with iron heads in my Super Stock 428. 330-ish intake flow, 250-ish exhaust with brass in the floors. Heads were 155cc intake runner, and 121cc exhaust, mandated 3/8 stem valves, 2.097 and 1.665 diameters. Current rules favor the aluminum heads, even with the weight penalty.
For "no rules" uses, the cost to get really good numbers is prohibitive, compared to several aluminium options these days. Mild OE-appearing stuff, truck towing engines, or CJ restoration stuff are the places to use a CJ head these days, in my opinion. You just can't get anywhere close to the bolt-on aluminum heads from BBM and TFS with OE iron.