Yours should be just fine. I put a 455 in my 81 Turbo 301. Mine had the ECM for the Dizzy and the Turbo lights in the hood. Just removed all that and used the regular Dizzy form the 350-455. Its really basic what wires are needed for the motor. Oil Press, Water Temp, Starter power, Alt wires, and Power and tach from Dizzy. All the sensors are the same between the motors too. Same Oil press, same temp sender. So if your replaceing those, replace them to what gauges you have in the dash. ie gauge or idiot light.
Factory harness should be fine. LIke Dan said, theres very little needed to make it run. 12v ignition source for the distributor(already there), and figure out what wires go to the water and oil sending units(already there). Starter solenoid wire (already there). The rest are most likely not needed.