There are plug wire protectors that you can slide on and then wire tie to the plug wires.
Spark Plug Boot Protectors - Speedway Motors, America's Oldest Speed Shop

Like mentioned, get some plug wires that you can cut to length yourself. Run them down and under the headers. Use some of those rubber coated wiring loom clips and locate them next to the block somewhere. You would only need 2 or 3 on each side. You can get them that will hold multiple wires.