Ive done multiple cars, and its not as bad as you think if you have a lot of patience, and have things appropriately disassembled. Removal of dash, kick panels, rocker sill, rear seat, etc, etc. . can make things go a lot faster. Take a ton of pics as you go through the process, and as noted, mark with masking tape what wire goes to what connector..and then mark on the dash, the firewall, along the rocker sill channel, etc, where things connect. Its obviously easiest is you can lay out the old wire harness with the new, and can swap out, swap in. If swapping in a used original harness, make sure to clean all connections, check all bulbs, etc.