Rusty is correct.
If you are going to run the lighter wire down to the starter, the left of the 2 larger posts on your solenoid in your picture (with the large battery cable attached) is where you want to go.
However...
I can see absolutely no reason not to just hook to the battery side of the ammeter under the dash.
That's just the other end of the exact wire running from the exact same place we just pointed you to on the solenoid.
And every lighter I've dealt with attaches that way.
Why run another wire through the firewall when it goes to and accomplishes the same thing as a wire that's already there?
Hope this saves you some work and wire. :-)
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