66 c10 Ls harness routing

[russellrox]

I am trying to figure out the best way to get my ls swap harness from the cab to the engine bay to look clean. I want to see some ideas on if it’s best to mount Ecm under the dash and pass through the firewall. Or if it’s easier to put it under the seat and run under the cab. I don’t really want to cut my new Nelson performance harness to extend it if I don’t have to.