I like the serpentine setup too, but your combination will dictate which way you can go.
If you want to keep a mechanical fuel pump you need to use an eccentric, adapter for eccentric or LA style long snout camshaft, and LA timing cover. That leaves with with LA V-belt setup or aftermarket serpentine setup.
If you are running an electric fuel pump you don’t need the eccentric and you can keep the Magnum serpentine setup, with some different parts to make it fit.
So, are you running electric fuel pump?
Is your battery tray in stock location or moved to the trunk?
Are you already planning to take it apart and check the heads or try running it as-is first?