All of them tapping or just a few ? Check the preload.

 

I just put LS7 lifters in my truck as well as 7.4 pushrods and I have no noise at all. Not even the typical Chevy lifter tick.

 

just cylinder # 1 around 1500+ rpms. He ordered a push-rod length checker today. Should be here this week.

I have checked/adjusted it three times now. Still the same so I'm assuming he might have to much pre-load or just normal lifter noise.

I did this same thing to my truck couple months ago runs perfect no noise nothing same exact rocker install as the instructions say haha except I have milled .03 heads and 7.35s