without having to find a new harness. Posi-tap connectors work really well and don't require any soldering which would be a real PIT considering how many wires there are that need to be reconnected, and in that cramped space. You can find Posi-tap connectors on Amazon. I used these when I wiring in my boost controller and aftermarket radio and have had no problems.
If you still need more wire or the connectors a cheap alternative might be to you scavenge from a Scosche CNN02 — Wiring Harness made for aftermarket installs in 300zx's. They're about $15 from Crutchfield.