Thanks to HWYSTR455, the problem has been identified. Mike, (HWYSTR455), installed and adjusted the new Crower rockers and we still heard the knocking. Turns out the knocking noise was coming from the torque converter. The noise was very deceiving because it certainly sounded as if the noise was coming from the back of the motor under, under the passenger side valve cover. We'll be checking the bolts to the flexplate and ensuring the flexplate isn't cracked. See video...
https://www.youtube.com/watch?v=V6UQfii_xOY