Just bought a 5.7 for my Duster

I am surprised no one has mentioned the 03 valve springs. They are weak. And are a common faiure. The 03 is no different form the other motors (oter than the valve springs and not having EGR) what makes a 03 undesiarabile is the lack of tuning on the 03 pcm. But if you don't have one, then you should look at finding an 04 or 05 pcm and harness. And if you go with the drive by wire the throttle body will need to match the 03 and 04 had a different plug from the 05.

a set of big valve heads and a properly sized cam will do wonders for that motor. You could chat with stu at inertia about your plans. He is a site sponsor and knows his motors.

I would stay away from a stock reground cam you will probably not see the power numbers your after. As you cannot make them large enough.

when it comes to efi, get the motor built and buy a diablo. Find a tuner and getting it up and running will be fairly easy for an experienced hemi tuner. (the best one I know of is in sacremento)