Took measurements for plug wires and got the starter cable completed. Here's the end result:
The starter wire snakes along the frame rail next to the main harness and passes under the steering column to the starter:
I'm going to go back and redo the wiring a little. I've determined I don't need the second breaker in the engine bay. There is already one breaker <12" from the battery and the alternator power passes through a 100A fuse in the main fuse box. I'm going to replace it with a bus bar or single post terminal to eliminate the loop in the starter cable and just in general clean things up.
I checked out the whole system again. Fortunately everything still powers up and the starter spins. I hadn't gone back and verified the system worked since taking C. Ludwig's advice about the primary ground.