Great to see a shot that shows exactly that ghastly crux move. Although it's now over 46 years ago, I can remember it as if yesterday, because I was teetering there with strength running out for about 5 minutes before I fell off. Pro was nothing like as good then: I simply had a huge sling round the block on the left (that your left foot is bridged against), so that the krab was way below the bottom of the frame. I ended up about a yard off the deck.