3/4 turn and still clacking?
Two things come to mind. One, did you soak those lifters in oil before installing them? If not, it may be that they just need some run time to get the oil going through them. That may "tighten" things up.
Two, 3/4 turn may not be enough with some set-ups. I know, some will be nice and quiet at 1/4 turn, others may need upwards of 1 and 1/4 turns to quiet them down. You don't know until you start playing with it.
I am not sure about your adjustment sequence, but I typically just do one cylinder at a time, one valve at a time. It is a little more time consuming, but once it's done, there is no doubts that each roller rocker was adjusted correctly.
I once had a set of Steeda 1.72 shaft-mounts on a set of E7s, stock cam, etc...it took a full 1 and 1/2 turns to stop them from clacking...and they were still a little noisy. I even called the Steeda tech line about it and they said everything was OK.
Now, my current set-up is with a much "wilder" combo and stud-mount 1.6 Scorpion RRs...3/4 turn.
So, adjustments can vary significantly depending upon what parts are used.