If you feel you are running the dog doo doo out of your 408. There is a very simple fix. More stroke less RPM same HP and a little more torque. BPE, Callies and many others have 4.250 stroke cranks. Then you can be a little easier on your engine and still get it done.

If you must, add 200 lbs to the front k-member so you feel like you are running a Big Block.

Seriously stroke is the quick answer to your concerns.

Leon