Nobody thinks the stock exhaust manifolds might be an issue? I had a 440 in my 69 charger with 10:1 flat tops, stock heads, Crane .484 cam, Torker 2 manifold, 850 dbl pump, Cyclone headers , 2 1/4" exhaust, accel dual point mech dist and 3:23 gears...that thing would roast the tires if you wanted to and would eat 5.0 mustangs and 350 vettes for breakfast back in the day....