There seems to be no end of lessons to be learned around here.
Seems it is in fact NOT a good idea to heat up the end of the extension housing to soften it to help straighten out that ding. It was not the aluminum case that suffered, it was the bronze or whatever it is bushing inside that literally melted. I found a puddle of what I would swear was solder on the bench where it had landed.
And the no one on earth seems to have any NIS-62 bushings available. Out of Stock is the key word of the day.
And full circle, I am now onto option 4 as above, go get a real 5 speed with the right bell housing and just put it in. Humph.