Re: old to new
2 ways you can likely go here...
With fuelie, you can try to piece together parts from mid-80s to 90s Mustangs, Explorers, F150s, etc. Best luck may be with the F150, as you'll find parts from 351s, not 5.0s. Not sure what vintage the 351W you have is, but this could cause some issues re: smog equipment, to run with the later model computer etc.
A better way may be an aftermarket injection set up, carb-style maybe, that you'd source from the manufacturer. Not totally cost effective, but in the long run you'd likely have a more complete starting point.
Ignition same thing. Maybe a FAST or MSD system or the like.