FYI - for what it's worth, as I deep-dived into troubleshooting this issue I reviewed numerous "Trans / Converter Installation" write-ups. I've attached a Turbo_Action PDF because it basically touched on nearly everything that has been described in this thread so far (including the specific recommendations you guys have provided).

In particular, take a look at P4 which highlights the recommended crank-to-flexplate bolt head thickness and provides a good explanation for why this needs to be checked.

In hindsight, I would have covered this had I actually pulled the converter out fully and mated it up against the installed flexplate to check for any such binding prior to installing the motor back in the car.