351c knock

ive been driving my 73 cougar to work this past week and have been given the time to work a little on it... new tires.... discs... drums... bearings. and so forth. but now im noticing a knock on the driver side of the motor (to mechanics thats the left side while sitting in the car) i know the motor is in dire need of a rebuild... since finding replacement parts (ie head, block, crank) are harder then finding bearings, oil pumps, ect. i wanted to do a rebuild. i hope this will cure the knock.

ive also done reading as pertaining to knocks, and i dont believe i fully understand. if anyone can help with more info... perhaps a better way of explaining. or how to get rid of the knock. im all ears and would appreciate hearing it.