I used 2 wiring kits from painless, a stock one and an 8 circuit race one (no longer available, 10 circuit only AFAIK). I completely removed all original wiring as it wasn't in very good condition. Painless stuff is easy to use as the wires are marked for the circuit. I did do some modifications as I ran a larger starter motor wire and a neutral ring around the car. I also bought a load of weather proof connectors for anything that had a plug and socket. The Electronic stuff is on Deutsch connectors. I changed all the lamps to LED's (bar the headlights, which is on the list for conversion) and a headlight relay upgrade
The stock one took care of all the stock stuff and was fitted under the dash. The race one is fitted in the trunk and does the fans, water pump, fuel pump, data logger, line lock. Which left 3 spare circuits. A bit overkill admittedly but it works very well and has provision to grow as I intend to fit a nitrous system and controller in the future.
HTH's.