V8 Engine
V8 ECU
V8 complete engine harness
V8 4x4 ECU
V8 4x4 dail
V8 Transfer case (No 2WD on them)
V8 instrument cluster
Once you have this you go from there and see what else you need. If you are an electronics expert than maybe you can make the the V8 function in 2WD mode like the V6 and not purchase the transfer case and V8 4x4 ecu and use the existing V6 parts for this.
It would probably be best to buy a wrecked V8 4runner as a donor vehicle than source all these parts separately.