66 Valient, Exhaust Manifold Options

What engine and heads are you running?
273, .040 over, forged flat top pistons, CR calculated at 9.1, Isky E4 solid grind, stock valvetrain, Edelbrock D4B, Carter 9636, Electronic ignition. I already have a modified single exhaust going into a Dynomax muffler and then into the stock HP resonator. Currently the car in the motor is a 74 318.