How to build a 13 second 340 Duster

A set of Performer RPM heads probably wouldnt be much more then what it will cost to redo the stock heads. I would however have the Eddys checked out, especially guide clearance. I think the best thing for you to do however is come up with a price range and talk to a few shops. See what they can do for X amount of money. Edlebrocks will cost you $1200 before having them looked at and arent needed to run high 12s. But if your heads need $800 worth of valves, springs and machine work it may be worth spending.