Noisy hydraulic tappets: something is wrong. Too much lifter body to bore clearance, misalignment of oil feed holes to the tappet, or not enough oil pressure.
Other cause: are you sure your rockers are doing the right thing?

A solid roller tappet is struck violently by the cam lobe's opening ramp during the lash take-up, large tappet clearance amplifies this, and the entire shock load is taken by a small number of needles (not even half) in the roller assembly. Not real numbers, but if the roller OD is .750", the roller ID has to be at least .375" (roller is 3/16" wall). Allowing for 1/16" needles, there are only about 16 to 20 needles , and only those at 6:00 position (5-6?) are loaded.They don't like it.