I might be thinkin' ProComp aluminum heads. There is at least one professional builder on this board who has used them and recommends them. Here's a brand new set of oval port 300's that are only 100 bucks more than what you'd have in your iron heads.
Procomp BBC 454 Aluminum Heads Complete 300cc Oval Big Block Chevy | eBay
Edit: Bob is the pro I was referring to.
He posted while I was typing.