If you can handle a jet engine, with the right repair manuals you should be able to handle the old six. If you have a friend that does mechanic work, he can help you.
As was suggested you can take a sawed off broom handle and listen to the side of the block to try to narrow dwn where the sound is coming from. Put one end to your ear, the other to the bock just below each spark plug.
If it is a rod bearing, a lot of times if you remove one spark plug wire at a time when you get to the loose rod it will quieten down some. That will be the one that is bad.
When you remove the plug wire, if it doesn't quieten the knock, put the wire back on the plug and go to the next one.
If you pull the oil pan, and look inside th engine, you will see the rod bearing and main bearing caps, but won't see te bearings until you remove the caps.
