That's a classic muscle car you've snagged. That fresh air setup alone is worth the price of admission. A 383 loves to rev and breath, so do the things that will let it and it will think it's a 440. What carb is on it presently, the original AVS? I see that it still has those beautiful Magnum exhaust manifolds. Headers may be slightly more efficient, but they create a ton of underhood heat. It's gonna look great in the copper with white vinyl top.
