Leave the long block assembled and pull the intake/valley pan and take a good look at your lifters....they are probably compressed too far and will not pump up on their own.
I agree , also take a look at pushrods closely , are they rubbing on the heads ?
And lastly are you sure the noise you atre hearing is not normal , Roller valvetrain , even hyd, is not as quite as the flat tappet with non adjustable rockers .
Dumb question , you did measure your valve heights so you know the springs are installed at the proper height to get the correct spring pressure , plus you measured the springs at the spec height to make sure they were right ?