Installing new wiring in my 31 Cabriolet

[Ed in Maine]

The power wire for the cowl lights in my wiring harness is about 8 in. long and has a male plug-in fitting at the end. It comes from the light switch. A connecting wire has a female fitting to receive the power from the 8 in. wire. My question is, how is the connecting wire routed from the engine compartment to the other side of the firewall where it will be plugged into the two cowl lights?

Thanks for your help, Ed