I have a 400/470 with E-heads in a E-body. If I was ever to build a bigger motor, I would use the TF240 heads. Those will give you room to grow if you ever change your mind about what you want out of the car, but still work quite well on the street with your CI. The right cam and intake will make a street torque monster. Call around for advise on the cam, and then pick the intake that works best. I don't know enough about Chargers to tell you which intake will fit under the stock hood.