Back to the project after a break when we had all the kids here. The firewall doubler for the fuel line overlaps the mount for the starter contactor. Marked a minimum edge distance on the rivet hole in that corner, then began working a notch in the corner to clear the mount and not violate edge distance. Several trial and error iterations and I had a notch that worked. I countersunk the rivet holes then scuffed the fuel line doubler, washer, and contactor doubler for priming. Washed and dried parts, then primed with NAPA 7220.