This was supposed to be a one hour job, at most. As it turns out, the mounting bracket style for the ignition coils has obviously changed and/or I don't understand how my installation manual wants these installed. Either way, I decided to move the mounting surface back by adding thickness in the form of left over spar doubler from the wings. I even added an additional .040" thickness behind for good measure. Even at that, the back of the coils was dangerously close to rubbing on the top edge of the firewall doubler, so I carefully removed a curved sliver of aluminum to eliminate any possibility of abrasion. Finallly, they were mounted with four AN5-10A bolts. These puppies aren't going anywhere.
Success at last
Here you can see the bar used to move the coils aft
Careful spacing of the bolts to miss firewall rivets