Well I know from experience that the electronic speedo on your '94 is plug and play for your 3RZ stuff, so that's nice.
I had Haynes and Chiltons manuals for both my truck and the doner vehicle and a tester. It's not too bad if you lay your harness, locate what's what by color and start going after it. It starts to make sense.
I chose to make a conversion column using the 3RZ steering wheel and controls. This way I could use the 3RZ harness straight up and just graft the tails, fuel pump and heater from the older vehicle.
There are better ways but I found this easier.
Check out the 3RZ thread it is a wealth of knowledge.