You can adjust half of them at cylinder 1 TDC and the other half at cylinder 6 TDC I believe.
This will only work with a stock or slightly over stock cam. With almost any performance cam, the ramps will start to open or close the valves a bit, too much when using this method.

Pat, I have done them that way too....I just have a preference for the way I discribed. Hey, how have you been? Not much going on lately in the big block forum....that's where I usually hang, and see you. Happy Labor day! John