Top 5 worst A-body repairs/restoration jobs
You guys have covered the jobs I was going to list based on what I've taken on personally.
Heater core was a collosal PITA. If I had to do it again, I would just pull the bench out first and saved my back a ton of strain. I have no excuse for why that didn't occur to me last time.
The power steering box removal- wow. I unbolted everything I could see that was in the way but it wasn't until I loosened the motor mounts and lifted the whole damn engine that I was able to get it out. It felt like pulling some tenacious, alien, octopus like parasite out of the mouth of some poor animal.
In the category of "this shouldn't be hard" I'll put torsion bar removal. One mistake can turn this into a nightmare. I had a case where something was apparently just ever so slightly misaligned and my brand new aftermarket torsion bar got jammed while still 6-8mm away from being fully seated. Not having done this before, I thought that the bar going in pretty much all the way was a sign that it was aligned ok and that it just needed a good whack. Well, that one last solid whack was just enough to jam the damn thing at about 5.5mm shy of being fully seated... it was jammed so tightly that even The Incredible Hulk himself couldn't get it loose. Not an exaggeration, I was on my back under my car on jackstands for 20+ hours (non-consecutive) trying to get that damn thing out without damaging the car. I tried heat, I tried cold, I tried doubling the torsion bar removal tools (for more grip) and using a bigger hammer. In the end, I gave up, got out the angle grinder and cut a section out of the damn thing. One end came right out of the control arm...but it took a tremendous whack directly on the stump to knock the other end out of the body mount. I ordered a replacement and accepted it as the cost of learning.