engine noise

[ame="https://youtu.be/XNqNt-FZv3M"]https://youtu.be/XNqNt-FZv3M[/ame]

I just installed a 5.9 Magnum that I had rebuilt. As you can hear in the video I have a ticking noise that does not sound right.
I hear the noise the loudest on the passenger side of the car towards the center of the valve cover around #4 and #6. It also seems loud under the car.
I'm not super mechanically inclined but this is what I've done so far to try and figure it out.

I've checked to make sure the flex plate bolts are tight and aren't hitting anything.

I used Remflex header gaskets that supposedly aren't supposed to leak

I've listened around the motor with a piece of pipe to my ear to try and detect where the noise is coming from. I listened to the timming chain cover, the fuel pump, oil pan, side of the block and the valve covers. The noise seems a little more pronounced around the valve covers, but I really don't know what I'm doing.

What are the next steps I should take to try and figure this out?