planning for this conversion down the road, I found the turbo 400 wires and plug under the dash. Know I need the gas pedal and switch. I can’t find any downshift wire in the engine compartment and assume I won’t because car is a 350. Should I order an engine wiring harness for a 455/turbo 400 combo? Will this then address this issue, avoid any other issues wiring up the 455 conversion? Car has air conditioning as well if that matters for harness. Thanks