273 Adjustable Rockers with Hydraulic Lifters??

I was hoping someone could walk me through the proper way to Adjust the valves on a 340 that has 273 Adjustable Rockers and Hydraulic cam and lifters.

The engine was built many years ago by father, ran for a brief while and than sat for a long time. I have it running again but there is some slight lifter tapping going on (Sounds like it is just in #1 Cylinder). I am hoping it is just a matter of adjusting the rockers but not sure on the proper procedure for this.