On a stock iron block with iron heads with a small or stock cam I would bring the #1 cylinder to top dead center on the firing stroke and then reset the lifter preload on both valves. I would feel and try twisting the pushrod before starting,(set one at a time) if it moves or not then loosen the lock nut on the adjuster a little at a time and lift on the rocker arm towards the valvs until you get a little bit of slop(up and down movement) between the adjuster tip and the pushrod. Once you have a little clearance slowly tighten the adjuster up while spinning the pushrod to determine when the clearances are at zero between the adjuster tip and the pushrod cup(take your time to make sure it is at zero with no preload or clearances ) When your sure and comfortable with the zero lash and zero preload add from 1/3 to 3/4 turn preload on the adjsuter and lock the lock nut down while holding teh adjsuter so it doesn't tighten up with teh lock nut . Adjust the preload on both valves and then rotate the motor over 90 degrees in clockwise motion looking at the front of the motor towards the drivers seat and set #8. If you want to do one side of the motor at a time then use the firing order to do that side, IE #1 firing at TDC is 270 crankshaft degrees away from #3 firing at TDC, # 5 is 180 degrees from #3 and #7 is 90 degrees away from #5. On the passenger side # 2 cylinder is 90 degrees before #1, #8 is 90 degrees after #3 and # 4 is 90 degrees after #8. #6 is 180 degrees from #4 IHTH and doesn't confuse the real issue of setting the lifter preload properly BTW, you will hear any where from 1/8 to one full turn of preload depending on that persosn likes and dislikes