SM Head Install... forgetting anything?

He's using the stock stamped rockers. Sounded like the lifter tap I had on my 360..

360LA Lifter Tap
And that case take a .010 feeler gauge and slip it under each one until you find the one that's noisy and it gets quiet... old school method... with a rag in palm of hand, with valve cover off and cardboard shield...push on each rocker 'pushrod side' till you find the noisey one and it quiets.