I tapped the 2
oil feed holes in my Eboks with a 12-24 starting tap, about 5/16" deep (no need to pre-drill). I then line bored the center of a 12-24 brass machine screw lengthwise with a 1/16" (0.0625") drill bit. I cut about a 1/4" section of the of the line bored brass machine screw and then slotted the one end with a hacksaw to enable screw driver installation/removal later. Thread your bored screw sections into the heads until they bottom out and snug them down. I had everything I needed laying around the garage. The whole process took about 30 minutes.
0.0625" restrictors, hydraulic roller cam and Erson rockers. 8000 miles on that setup with zero problems.