ILG,
You stated that TWA's blocking the Flaps 40 was for an unrelated reason, but I can tell you that while in 727 class at TWA we were told specifically that the Flaps 40 setting was blocked as a direct result of the SLC accident, related to excess drag at flaps 40. Had they been at Flaps 30, the sink rate could have been arrested and there would not have been a problem.