the two set screws. plugs in the lifter valley where the heads get their oil. these are the small 1/8" ones. you select the drill bit size so you can tap that hole for them. you drill completely though into the oil galley then into the oil feed galley to the heads. you only tap the top hole and then Loctite the plugs in. you should turn the #4 cam bearing upside down and redrill the feed to it from the #4 main. this gives you full time oiling to the heads and no pulse oiling to the rods on each side of the #4 main. all the bearings at #4 now get their supply of oil and don't have to share any with the heads.
before you drill take a extra long drill bit or a 1/4" rod and slide it down into the oil feed to the heads so you can line up the drill bit to get the angle correct. you can see in the pic that the oil feed to the heads isn't in the center of the hump if you look where it is at the deck. matter of fact both sides in the pic aren't even the same so you have to drill at a different angle. see the plugs aren't in the same place on each side. the bottom pic clearly shows how each side is different at the deck. one side is in the center of the hump and the other is off to the back of the hump. line up the bit and drill slow and easy and take your time.
