There is a few hurtles with wiring
1. Pats either tune it out or get a stand alone computer.
2. Emissions the stock computer wont like the rangers evap system so the the donor stuff will need to be used or tuned out. Passing an emissions inspection if your state requires it.
3. Vss signal the trans wont shift right if its not getting the correct signal so if it comes from the trans your good but if it comes from the rear axle some reaserch is needed to see if its compatible.
4. The obivious power and ground wires starter and altnator are simple circuits to make work but you will need to find the pins in the engine harness to supply power to the pcm and the grounds it will need a few hours reading schematics will help with that.
5. As far as the ranger body harness is concerned leave it in. You just need to tap into it for check engine light, oil pressure, obd2 plug, coolant temp, and battery voltage. Now as far as if your gauges are compatible with the 4.6 im not sure.
If it were me id focus on fitting that wide pig in the engine bay and get the cooling, power steering, and trans cooler all buttoned up then move to fuel and air. Once thats all buttoned up get a drive shaft in it because theres nothing worse than getting it running and not being able to do v8 burnouts and pissin off the neighborhood. Then start wiring.