1969 Engine Bay Wiring Problems

[67ChevNut]

I am doing this TBI conversion and I am unable to connect the following wires on the pictures here. One picture shows two wires coming out of the firewall right above the engine wire harness plugs. The bigger wire starts at the ignition switch, but don't know where it goes, and the smaller yellow wire either. It appears somebody messed with them before and they were not properly connected. I am thinking one of them goes to the starter or battery. Like to know where they are supposed to start and where they are supposed to end. I looked at the wiring diagrams already and still having a problem identifying them.

The other pics. are connectors from a starter wire harness I bought from classic parts. I need to know where the black connector with the pink wire goes to, I believe the white connector goes to the HEI distributor. Can somebody help me? Appreciate all replies.