Gen 3 HEMI Torque upgrades?

Daemonkey,
The 6.4 makes 475 lb/ft of torque stock and the 6.1 with the right cam should get you the torque you are looking for. This is the results of a cam swap in a 5.7:
Hemi Horsepower Helper: 100 Horsepower Cam Swap
The 6.1 has much better heads than the early 5.7 in the above article.