Help! Small block 360 has a knocking sound

There are only two things I have ever heard make that sound;
1) is a wrist pin, and
2) was a flatted lobe,
But the the lobe was a whole bunch quieter, and was of a slower cadence..

I've never heard of anyone getting away with 200psi, with iron heads ,on the street,which is all I know.

Isolate the cylinder by removing the plug wires one atta time. When you find it, check for rocker arm play with the piston parked at TDC compression. If none then suck the piston down the bore a half inch or so be hand-rotating the crank. Then insert a metal rod thru the plug hole with one end resting near the center of the piston.Then attempt to push the piston down. If the wristpin is loose the piston will drop down a few thou,easily, then stop. Back the crank up a few degrees and repeat to verify.It will be obvious.