Update: Project is basically complete, aside from a few minor finishing details.
To straighten a bent clamshell, rig up a way to fully support the clamshell except for the bent side. Heat the clamshell with a heat gun until it is uncomfortably warm to the touch, and then place weights on the cantilevered bent edge so to push it back down into place. In my case I used plastic totes of old car magazines since they could be stacked securely one on top of the other.
Patience is the key here, as you need to repeat this process many times, slowly increasing the weight (i.e., adding just a few more magazines each time) and carefully measuring the results after an overnight's settling and cooling. Eventually after around 15 or so iterations (I did not bother to carefully count) over 6 weeks or so I got the two edges to match again, down to a height comparison difference of roughly 1 mm, one side compared to the other.
At this point, you are basically done and ready for reassembly. Four pictures taken this morning:
The clamshell gap edges and elevations when the top is both raised and lowered are still not 100% perfect when compared to the adjacent top edges of the fenders and the forward edge of the rear trunk. But to be honest, they likely were not perfect before the accident in the first place, and I never was bothered then. In any case, I can live with it.
All that remains to be done is to clean the top, polish/wax/seal the surrounding paint in the area (pictures show the dirt and smudges), and then address a couple of minor new cosmetic 'ripples' in the clamshell's sheet metal. I now have a paintless dent kit on order and I will see how that final work goes. Worst case, I can always visit one of those paintless dent job shops and turn them loose.
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Moral to my story: This drama all stemmed from a twisting shear failure of the right-side square cable between the central top motor and the right-side top transmission.
Are the cables on your car original, such that the old internal grease has long since worn away? If so, yours is an accident just waiting to occur without warning, just like mine. Do yourself a favor and order a pair of new cables and replace your old ones as a preventive maintenance measure. It's fairly easy work, and the couple of hundreds of dollars spent on new cables could save you thousands of dollars (and yes, that's literal) in failure repair!
DM