I used the original Chevy outrigger type plug wire looms. They bolt on the ledges behind the heads. If you look at the rear of the block on that ledge on each side, you'll find an unthreaded hole and a threaded one nearby. That's where the outriggers bolt on.

The two rear plugs on both sides are pretty straight forward as far as routing.

The front two on each side run between the exhaust manifold and the block. You can buy the small two-wire looms that are held in place with one of the pan bolts (each side). The front wires are then routed through the engine mount to 1-3 and 2-4, respectively. You may have to lift the engine off the lower mounts to do this.

Long is good.