Follow the oil cable down, between the Center & Mag carbs, it should be a 10mm bolt on top of the oil pump. It's best to remove the carbs you'll get a good look at it that way.
Hmm... The pump on my redhead doesn't look like that at all. ANyways it's either on that line in the Diagram Blue posted or it is right down on the pump itself. It would be a bolt that points up....