Building my first 440

Sounds like the 906 would be enough for a mild performance 440, especially if he already has them. It’s easy to get carried away with shiny new things and high horsepower parts when they’re not really needed. My B body cars have all been 440 cars with cast iron heads, and they’ve all done a great job of bringing it when needed. Unless the OP is planning on getting carried away later and prebuilt a few things, I think he’d be happy with iron heads, especially for cruising around, burnouts, and similar tomfoolery!