I put a painless kit in a cruiser once. Was fairly easy and took a day to do, but I know automotive circuits fairly well, and this was a Chevy V8 and chevy column. The kits are labled well, but usually require attaching to a connector pigtail, unless they have changed them in 10 years.
The hard part will be wiring to the dash, turn signal, and switchs as they will only be power leads to those circuits. You will have to use or make the rest of the circuit. The engine and lighting circuits are good.
Like thorvald mentioned it is a good learning experience, and you will understand the wiring of your rig when done. But if there are only small things to correct, just fix your harness...go for the painless if its far gone and needs most things replaced.
Good luck