I think the Mopar Performance Stage V iron cylinder head is still available, it is very much like the 906 but with a better exhaust. If you run the Max Wedge iron head you must find a dual plane intake of Max Wedge size for a 383/400 block. I can't think of one offhand.
Read this carefully, http://www.forbbodiesonly.com/moparforum/showthread.php?64775-Pop-s-440-is-near-ready-to-dyno&highlight=Pop%27s+440 there is a great deal of information on what kind of horsepower you can get with a small flat tappet hydraulic camshaft and the factory 346 iron head and a dual plane Edelbrock Performer RPM intake. The Stage V or the 906 is capable of 25-40 cfm more than the 346. Problem being, the Stage V or 906, fully prepared to produce those flows, will cost you as much as your present engine.