Thanks for the replys.
I was able to find independant sources of data to answer my question too. One J30 was 90-100 miles south of the worst weather that night and was ending a trans-at crossing. He reported being rolled to 120 degrees because of stains on the overhead suggested this. There was not and never has been corroboration of this angle.
The other J was racing and was in the infamous 40 mile circle that saw the worst weather that night and next day. The crew wrote that they were knocked down to an angle that placed the spreaders and mast in the water, suggesting approx. 100 degrees heel. The boat stayed in that position "about a minute", before righting herself. this suggests at least a minimum of righting moment remained at +/- 100 degrees. I think it was largely a matter of luck that another wave or strong gust did not strike her whilst laying on her side and roll her inverted, like what happened to so many vessels that terrible night.
