1990 318 rocker arms

Hi all, I am re assembling a 1990 roller cam 318 from a truck. It is for my 70 Duster. When I took it apart I found some shaft mount rockers replaced. What I have now is some rocker arms have a offset hole in the pivot point of the pushrod and some do not. All pushrods are hollow. What is the correct rocker arm for this engine? I assume the hole is for extra oiling.
Also, how much preload should roller hydraulic lifters have with the pushrod from factory?
Thanks