I dont think the bomb racks (3 x septuple carriers) were recovered from the scrap yard, it was the carriers for the Shrike, hung on a load of carefully cut angle iron, fresh from the regiment's barb wire stocks, that were recovered. Bomb Racks a plenty at Waddington in '82.
The NBS may have been clockwork, but it still got the bombs somewhere near the islands.
The angular bomb run simply gave the stick of bombs a few thousand feet left or right of target centre, to hit the target, if the stick was dropped bang down the centre line but was +/- 50 feet, they would all miss.
The best bit of the Black Buck raids, was sitting in the very cold bomb bay being dripped on by very cold water, whilst the rest of ASI was baking.
A very nice BEFORE picture.....