check for pushrod rotation when running.
May need to rev it to get rotation. ya I know it makes a mess.
If yu cannot see pushrod rotation at all on that noisey rocker:
You may have a cam lobe or lifter foot going south.
or could be a internal lifter oil dirt issue.
Or the rocker arm is fubared.
These cams are never perfectly quiet.
Now that you got good oil in it.
Some times readjusting the rocker nut a few times wil free up a sick dirt infected lifter oil metering valve/ball.
Give it some driving time and see if it improves.
Mine was pesky at first.