A neutrally balanced torque converter from a small block 727 will bolt right up to a 2000 5.9(360) after you elongate one of the converter holes in the flexplate.
The serpentine setup is nice, but with an electric fuel pump, some Summit headers (driver's side is tough to fit on in the engine bay but easy when installing engine and trans from underneath), a center sump milodon pan and pick-up, throw in a new double roller and tensioner. mount battery in trunk or get a narrow battery out of a Ford School bus secondary battery and cut the mount and weld it up, Use a 1973 style radiator from an a-body with driver's side inlet and passenger side outlet. Good luck on finding a shroud. There are two fans available. Use the smaller 5 blade one. The other has like 9 blades or something and it sounds like an airplane is about to take off.
I put a 2001 in my '68 and kept the EFI. I love EFI now, but there was a learning curve. Unfortunately for me, the #2 cylinder only had 90 psi cranking compression from worn rings. it was still a mid 13 second car with 3.23's and a 727. I'm swapping it out now with a fresh 408" Ported Eddie headed motor, bigger injectors, a new SCT flashed tune, an automatic with OD and 3.91's.