I used
Hot Rod Wires 12 circuit harness in my '56 and I bought another to put in my '54 pickup.
A lot cheaper than Painless and bigger wires where it counts. Very good instructions.
I bought a Painless harness from a guy who had given up on his project. I considered using it on my pickup but after looking it over, I sold it at a swap meet and bought another Hot Rod Wires Harness.