How do you route spark plug wires to distributor for 89 Chevy caprice?

Just follow the side of valve cover(s) & drop down between exh. ports. You can get those holders from an auto parts store to suspend the wires. The routing is entirely up to you. The factory does not always know best. You want to keep them as short as you can, prevent boot burning, & separate to avoid crossfire. I always use a universal set when replacing so I can cut to length.