glad you guys already corrected the myths about the 346 - 452 heads. There's been a lot of work done on this, I think even here on Moparts in the Tech Archives are some articles with published tables of flow data showing that in bone stock form there is a slight advantage to the 906 heads, but that all the open chamber heads pretty much even out with port work.

The question in my mind always comes back to whether it makes sense to sink a pile of money into factory iron heads. If you can do your own port work then sure, why not spend your time on that and spend the leftover coin on other goodies. But if you're paying someone else to do the work it gets kinda iffy on which way you come out ahead.

Another note- if your 440 is "mild" you need to be aware of the effect of aluminum heads on combustion chamber behavior before you consider going that route. The rules about compression ratio and fuel type change between iron and aluminum heads