Putting the plugs back in required using my other new tool -- a gigantic
Craftsman torque wrench. I had my A&P set the torque properly the first
time, just to make sure I wasn't mis-reading the danged thing and twisting
something off inside the engine.

If I read this correctly, you got the torque wrench that "breaks" at the
torque set on the handle.
When you finished, did you "properly" store the torque wrench?
(Just a test to see if you read the instructions that came with the
tool.)