Long plug wires - where to buy?

[72 Cheyenne K20]

I have a 72 with a 350 and am getting ready to switch from points to HEI. The dizzy is the easy part. The pita is trying to find the plug wires. I'm trying to go factory and need the wires that are long enought to go behind the motor instead of over the valve covers. I've been to six different parts stores and 2 GM dealers and no luck. I found a set in yellow but want black. I know they must be out there, any suggestions on where to find them?

Thanks, Scott