@PJ2 - not sure where your post's gone, but...
Going back to my notes, it took about 16-18,000ft to recover the way we did it. My writeups are on the last page of thread 6 and the first page of this thread.
We did not reenable ADR or FPV during the recovery, so I don't have the numbers available that you do. This was purely seat-of-the-pants stuff, applying ND until the THS returned more-or-less to the centre and holding the dive to gain speed, correcting the adverse roll with rudder inputs and gently pulling out of the dive once we figured we were going fast enough to be flying again.
Our experiment was purely qualitative - proving that the aircraft could be recovered if the situation was correctly diagnosed in time and that the aircraft's systems would in no way impede the recovery.