Thanks for the photos. Good for future reference.
NOTE: One thing you did not mention, which may be obvious to many readers, but it totally slipped by me when trouble shooting front brakes.
The car would dart to the right on hard braking. No adjustment would prevent it. All new bushings and ball joints - nothing loose.
Pulled drums. All new parts from prior owner. I had drums turned. Reinstalled - no help.
Finally took it down to my local independent repair shop. He pulled the drums and immediately noticed that the shoes were installed incorrectly.
Right side had both of the rear shoes (longer lining).
Left side had both of the front shoes (shorter lining).
The shop R&R'ed shoes in proper position and that solved the problem.
NO SUBSTITUTE FOR EXPERIENCE !!!!!!!!!!!!!!!!!!!!!!!
I had forgotten all about this little tidbit since I hadn't worked on drum brakes since the mid 20th century.
Now for the good news:
Before getting the brake shoes installed properly, I was driving about 45mph in the hill country at night and a deer darted in front of me from right to left.
I hit the brakes and the car darted to the right just enough to miss the deer. I guess the Chevelle gods were watching over me.