The replacement upper right engine mount attach bracket arrived today so I got back to work on riveting the firewall.
The new bracket aligns much better.
The AN426AD4-5 rivets are a bit too short for the steel brackets so I decided to use AN426AD4-6. The ideal length would be 5.5 but half sizes aren’t readily available. There aren’t enough in the kit so I ordered some extra. They haven’t arrived yet so I had to pause for now. I completed most of the remaining firewall rivets.