I made a comb out of thin ally, but couldn't find it the last time I needed it, so I used one of those magnetic screw retrievers to position the pushrods prior to trapping them in the rockers one at a time. Had the rocker box raised about ten mil.
I could just get a finger in to finally check all four were located, but cranked the engine very slowly for the first turn just in case I had mis-placed one.