Lifter Knock??

[Nuke427]

Okay, I finally get my car out after swapping intakes and getting my awesome BIGS carburetor on. Car runs excellent. But now I hear something new. After some spirited driving, when I pulled into a gas station I hear a "knock". Kinda quiet, but noticeable. If I rev the car you can't really hear it anymore, but these things are so loud, I believe it's just speeding up the knock. The knock is definitely louder right after I rev the car up, then it kinda fades away but is still there. I do not notice it at all when the car is first started cold, actually I don't notice it until I do some spirited driving or after a little bit of use. Could this be a lifter? It's definitely deeper than right below my valve covers. Also seems to be more pronounced on the passenger side. I don't really want to tear off the carb and intake again if this may be able to be solved with a rocker adjustment or something. Please reply asap b/c I'm letting the car cool off in the garage right now and plan to start "digging in" to find the problem.