Nick Crump

Hi, I have just completed a rebuild of a '74 260z which had been off the road since the mid 80's the engine had been messed about with a little bit and came with a lot of extra bits and pieces. I think there is a part missing but not sure exactly what it is and wondered if any of you guys could help please. There is a fixing plate the comes off the rocker head at and angle and has various fixing slots in it and i believe has a part fixed underneath it. The photo attached is with arrows pointing to the part i am trying to find out about. Welcome any thoughts please. Thanks Nick