Hi all,
As this is my first post, I wanted to quickly say Thank You to everyone who have posted their experiences and expertise in all things JK.
Now on to my dilemma. What on earth is this noise?
Background:
Mine is mostly with IH, Chevy, and Ford. Mostly old school, pre-1980. But now about my JK.

The engine was seized, but the trans was recently rebuilt, so I pulled the motor and did the following:
2010 JK Saharah 4-door 4WD 2.5"lift
Manual Trans
Reputable shop rebuild:

• 3.8L, 0.020 over
• New Cam, lifters, pistons, bearings
• PS Pump, Alt, starter,
• Pulleys/tensioner,
• Water Pump, Battery, Spark
• Plugs/wires, S belt, oil, coolant,
• PS fluid, new clutch, pilot bearing, release bearing

1-Start up
Found TDC
Removed Fuel Pump fuse and plug wires pre-oiled by cranking starter for about 2 minutes intermittently. (Sounded fine)
Checked oil and topped it off
Replaced fuse and plug wires
Cranked it and it immediately fired up

2-The issue
Idle is smooth, but it sounds like a really bad lifter tap and like it's running under water (you can hear both in the video).
I have only ran it in this condition for about a 2min to try and diagnose the issue.

Any recommendations from those who have heard or experienced something like this with these motors? Any and all help will be greatly appreciated.
I will be following up with the rebuilder this week, but thought I would document this issue here for anyone attempting something similar.