The diff was chained down and straightened within 30 minutes.
The main bent issue required a little heat to get it to relax enough to reset it back to the correct alignment.
It was bent pretty bad, over 1" out of alignment at the wheel bearing position.
It was then noted that the other end also required a very minor jacking which did not require any heat to correct.
Concerned about the accuracy of my unit, I took another Ford 9" diff which had been repaired and straightened professionally and set it up with my alignment tools to see if I was any where close.
I was satisfied to discover that it was also true with my alignment tool and was perfect, so I take tow things from this exercise;
Firstly, that my straightening works works as anticipated,
Secondly, that my alignment tool is true and accurate.