I picked up a used 2000 5.9 Magnum, swapped the valve springs, did a Keg manifold modification, resealed the motor and put a Hughes cam & double roller timing chain in it.
I went with the factory EFI using a PCM from a 1999 Ram pickup with 5 speed & no security from SOLO PCM's in Florida. I had the PCM reflashed using an SCT handheld programmer, and bought a Hotrod Wiring Harness from Hotwire Auto. It only took 4 wires to hook up. The bigger cam and reflash really helped wake up the motor. I bolted it to a used 727 and installed a surge tank system for the fuel. I was running a set of Summit headers which worked fine and were very reasonably priced.
While the initial expense and learning curve of swapping to EFI was a bit steeper than throwing on a carb, the performance and drivability of EFI was a great enhancement, and was easily adaptable to my later engine upgrades.
In addition to having loads more power, the swap increased my gas mileage significantly when I stayed out of it.