First, my apologies for the speed typing earlier: I meant to state Explorer Oyster - its an Oyster as you state.
Given the evidence in your article I am inclined to think (despite being informed that this was an earlier Air King model) that this was the Oyster Perpetual you list in your article. No Explorer, no Explorer prototype, but just the Oyster Perpetual. I have amended the article and my response accordingly and stand corrected. Great research on your part. However, as stated, with the documentation, this is Hillary's Rolex from the expedition.
Hope this helps. I will confess that I am not a Rolex expert and hence was informed by Beyer that this was an Air King - although I now think that to be an error.
Andrew H