Yea, unfortunately Intel doesn't publish what the TJMax is. I do know that its published TJmax can change from different processors in the same series e.g. two q9450s could have a TJmax of 98 and 100. And I believe its documented somewhere that they have the ability to change it from core to core on the same processor.
I think us overclockers need to stop using imaginary temperature calculations and start going with TJunction, ive made the switch.