The cap and rotor on those things is easy yo screw up, double check your work.
If you want to rule out spark plugs go buy cheap ones, like the $.99 ones, those those in, what happens?

 

Update:
I retraced the steps I did for the distributor base pick up plate. I saw everything was together, nothing loose. Cables were snug tight, replaced spark plug #1.
and this is the outcome:
While, the knocking has stopped being like a "popcorn" effect, it is now knocking with the engine, and it's still coming from where cylinder #1 is at.