Wiring Harness info needed . 73 Duster .

I have a 73 Duster 340 clone made from a slant 6 and the firewall forward harness is in bad shape i got a mint harness from a 73 340 Duster does anyone know if it is a plug and play or are they different ? the car is an a/c model and so is the new harness , I can't seem to find a diagram .

Thanks .