318>383 swap ('74 Valiant)

After using them personally, I'd recommend the Schumacher headers for your project too. You might give up 20 or so horsepower, but the ease of installation coupled with the great ground clearance make up for it. They aren't cheap, at $500 but I personally wouldn't go any other way. By the way do you know the Dudesons? Love their show. Sisu!