Peak HP at 6500 means peak torque around 5000 rpm. For a 512 motor that means you need a CSA of 3.65 sq inches which is exactly what a MW port gives you. Any Indy head such as the 440-1, SR or EZ head that is ported to the MW size should put your torque peak right around 5000 rpm.

The Chapmans will do the trick also if you can afford the steep price tag. The Chapman heads are probably the very best BB Mopar head available in terms of airflow efficiency but most people don't care too much about that unless they are competing under certain rules.