ol' slant is dead... need help!

Aside from the random comments and arguments that have been added to my questions... I changed the oil last night, drove it around for a bit then let it idle. I did notice the oil change has made it only knock while I'm accelerating or in the higher rpms at least. Still not sure where the shavings came from especially since they weren't coming out of the pan. What I've gathered here, I'm going to change the oil pump next since it drives fine, no loss of power or overheating that I can see. The motor was supposedly rebuilt but I can tell if that's the case, it wasn't done very well.