84MonteSSCarlo

I have an 84 Monte Carlo SS with a rebuilt 305. The motor is not an L69 and the original wiring harness is in use. There are wires cut everywhere and the engine doesn't fire but turns well. I want to strip everything from around the motor and leave only what's necessary to make the thing run. After the thing is running and looks decent I will sell it and buy the 383 I need to go down the 1l4. Is the wiring harness important in Chevrolet and what else can I disconnect and still run properly? Any help would be appreciated.